Cruise vacations consistently rank at the top of vacation value and satisfaction polls. Most people who take a first cruise end up taking another one -- or dozens. Why? Cruises offer high standards of service and excellent cuisine, but the convenience factor is likely the main reason. In one transaction, you arrange your accommodations, meals, and itinerary for your entire vacation. You can cover thousands of miles and visit a dozen exotic destinations - and you only unpack your luggage once.

A Ship for Every Cruiser

There’s a perfect ship for every cruiser. This "cruise primer" can help you find your dream boat and select the style of cruising that best suits you.

You can cruise on a river boat, a small ship, a big ship or a mega-ship. (As the old sailors' joke goes, never call a ship a boat -- a boat is what you get in if the ship is sinking.)

There are cruises that provide intellectual stimulation - and others that focus on the complete opposite. Some cruises offer up-close encounters with nature, while some ships are giant floating cities where you can easily forget the ocean is “out there somewhere.”

Some ships are great for families with young kids or teenagers; others are preferred by retirees craving peace and quiet. Today’s ships can even accommodate road warriors who need constant access to the office via e-mail and cell phone. In fact, many modern cruise ships can handle all of the above at the same time.

By explaining the differences between various cruise lines, you can come closer to finding the perfect cruise ship for you. Below is a basic synopsis of the cruise industry, with a description of the cruise lines available to North Americans and the kinds of vacationers they appeal to.

A Category for Every Ship

The industry includes four basic categories of cruise lines. Roughly in order of increasing price, they are: Contemporary, Premium, Deluxe and Luxury. The contemporary cruise lines are the biggest brand names, and carry the most passengers on the largest vessels. They are the most popular, but certainly not the only brands you will recognize. Some people refer to these as the “mainstream” cruise lines.

A Synopsis of Mainstream Cruise Lines

Carnival Cruise Lines: Since Kathie Lee Gifford first sang “If You Could See Me Now,” people have known Carnival Cruise Lines as the “Fun Ships.” They live up to the moniker, with impromptu conga lines in the dining room and wacky pool games like “Belly Flop” and “Men’s Sexy Legs” contests. As trite as it may sound, the formula works, making Carnival the world's most successful cruise line. The spirit of fun permeates every person on the ship -- including the crew, from deckhands to captain. Asked to describe what type of person Carnival appeals to, former CEO Bob Dickinson once replied, “Everyone but curmudgeons.” Everyone finds something to like about this budget cruise line, and some people will cruise no other.

Royal Caribbean Cruises: True to its “Get Out There” slogan, this line delivers action and adventure onboard, with an abundance of shipboard activities and cutting-edge architecture. Royal Caribbean has the biggest and most technically impressive ships at sea, including the newest “World’s Biggest Cruise Ship,” Oasis of the Seas just introduced in December 2008. Oasis can accommodate over 6,000 passengers and 2,100 crewmembers. It has an outdoor “Central Park” with creeping vines and real trees; a separate outdoor “Boardwalk” with a real merry-go-round and an AquaTheater for water-based performances a la “O” by Cirque du Soleil. Other entertainment includes professional ice skaters on the largest ice rink at sea – also open for passengers who want to rent skates between shows. The main theater shows the first licensed version of a Broadway musical at sea: Hairspray.

Norwegian Cruise Lines rounds out the mainstream category. The line's forte is “Free-Style” cruising – meaning there are no set dining times or table assignments, and a variety of ongoing events and eateries. Its newest ship, Norwegian Epic (to debut June 2010, with 4,500 passenger berths), has no main dining room or theater. It offers 21 different restaurants, several nightclubs, and an array of entertainment options. Cruisers concoct their own cocktail of cruise fun by selecting different dining and entertainment options every day and night. The ship will feature entertainment by the Blue Man Group – the hit show from New York and Las Vegas -- as well as comedy from Chicago’s Second City Troupe and a unique Cirque dinner theater that may remind you of a Renaissance Fair production with its irreverent revelry.

These mainstream cruise lines have two things in common – they are based in Miami, and their megaships are considered destinations unto themselves. These mainstream ships mostly sail to Caribbean ports of call (they also venture to Alaska, Mexico and Europe), but the “ship as the destination” mindset is the hallmark of mainstream cruising.

Moving Up to Premium Cruising

Next up the ladder, in cost and sophistication, are the premium cruise lines. No doubt you have heard of these companies, but you may not know they cater to more intellectual mindsets by including lecturers and other enrichment and sail to more rare and exotic locations. Their ships are smaller at about 2,400 passengers apiece, lending a quieter and more personal touch to the onboard experience.

The premium cruise lines include: Celebrity, Cunard, Disney, Holland America and Princess Cruises. Premium cruise ships are smaller in size, but with fewer passengers they offer more space and more crew members per guest, for a heightened level of personal service. The food is generally better and the décor is decidedly more opulent than on mainstream vessels. Most important is the variety of itineraries on offer. With the exception of Disney, they travel worldwide from New Zealand to the Norwegian North Cape. And don’t let the word “premium” derail you – these ships can be as affordable as the mainstream lines.

Remember that the cruise lines in any single category can still harbor vast differences, especially when we start to examine individual ships. For example, some Princess ships are as big as some Carnival ships, but they are roomier and sail to more exotic destinations. The newer Celebrity ships (called the Solstice class) are even bigger, but they carry 30% fewer passengers making them roomy and architecturally radiant. Disney ships, on the other hand, mostly sail in the vicinity of Orlando, with rare trips to Europe or the West Coast, and their entertainment is all Disney for appeal to kids and other Disneyphiles.

Holland America, founded in 1873 but now headquartered in Seattle, has the smallest of this category on average, catering to a mature mindset with string quartets, cognac and cigar bars and a wide variety of world destinations such as South America, South Pacific, Europe and South America.

Cunard is the last cruise line to keep any semblance of the classic ocean liner “class system” in place, as in the movie Titanic. Cunard's Queen Mary II is considered "premium" only in its regular class, but it qualifies as a luxury line in its upper class staterooms -- like the Queen’s Grill category, where the cabins are all suites with butlers, and the cuisine is served in a private restaurant. Cunard, founded in 1839, is rife with seafaring history and the majestic Queen Mary 2 is the only modern ocean liner offering regular transatlantic crossings.

Deluxe Cruise Lines

Next we have deluxe cruise lines, including Oceania Cruises, Azamara Club Cruises, the new Voyages to Antiquity and Windstar. These cruise lines can be defined as “budget luxury cruises.” They are much smaller than mainstream cruise ships, 700 passengers or less, and put the focus on unique, port-intensive itineraries. With a different port each day -- and even offering overnight stays in certain ports -- deluxe lines focus on the travel experience first, but include top-notch restaurants and comfortable staterooms, so you can be fully revitalized for your next day’s sightseeing throughout the cruise. There is little entertainment onboard and no children’s programs.

Luxury Cruise Lines

Finally we have the luxury cruise lines: Crystal, Regent, Seabourn and Silversea. These lines offer the finest cuisine and the most spacious and comfortable staterooms at sea. They have butlers onboard and will keep your personal refrigerator stocked with your favorite wine, champagne or beer included in the cruise fare.

Luxury cruise lines generally offer only open-seating restaurants, so you dine whenever you please every night. All spirits, wines and even champagne are included in the cruise. These ships also include staff gratuities in the fare (on other ships, the average is about $10 per day per passenger). Luxury ships tend to have the finest cuisine at sea: Regent has Le Cordon Bleu, Silversea has Relais and Chateaux, Seabourn features food by Charlie Palmer, and Crystal has food by Nobu, among the most famous sushi restaurants in the world.

Note: Although Crystal qualifies as a luxury line, its pricing is not as inclusive as just described. Tips and alcohol are separate. However, the line has been running an “inclusive” special since 2009 worth about $2,000 per couple in shipboard credit with every booking.

What’s Included on the Average Cruise?

Except on the luxury lines, you are expected to pay for all your alcoholic and soda beverages onboard. You will also be charged for tips for the staff, generally $10 per passenger per day. To track these onboard expenses, you submit a valid credit card upon boarding, and all your shipboard charges are posted to your stateroom account.

You can also charge shore tours provided by the cruise line, and you can get advances for the casino from the credit card that anchors your shipboard account. There are usually plenty of gift shops on all ships, and you can also spend additional money on photographs, dinner reservations for special dining rooms, and massages or other treatments in the onboard spa/salon.

About Cruise Pricing and Value

When you see a price quote on a cruise, you can be sure that most sources are offering the same price, including the cruise line itself. Years ago a practice called “rebating” gave the price advantage to large volume sellers who rarely offered the best service. To reinstate a level playing field, the cruise lines now set all cruise prices and enforce a “flat-pricing” rule for all sellers.

The only exception to this rule is group pricing by special affinity groups offering a package deal cruise and special onboard events included in the price. Group cruises can only be attained through the agent sponsoring the group, and they will tell you that.

Cruise lines hate to see a cabin sail empty, so they have become expert at filling their ships by using price discounts and other incentives to entice vacationers. The industry reported 100% capacity last quarter.

Savvy consumers should try to “buy low and sail high,” booking cruises that the lines are discounting because they want to fill their ships. There is nothing wrong with these cruises. The lower prices simply reflect lower-than-expected demand for a perishable commodity. From the cruise line's perspective, some revenue from an empty cabin is better than none.

Thus you might think that last-minute bookings will always provide the best cruise bargains, but it isn’t that simple. 

With clever computer modeling, the lines can offer enough attractive prices to sell most of the cabins on a given cruise six months before the sailing date, and rates can often go higher for the remaining vacancies.

A cruise is a great vacation value: The price includes not only your accommodations on the ship, but also all your meals, entertainment and transportation to exotic ports of call. Regular cruisers know the value proposition cruises offer, so they book early to get the best selection of deals. Cruises generally earn a higher satisfaction rating than other types of vacations, and on any given cruise, most of the passengers have cruised before and will again.

CruiseMates Cruise Glossary

I started writing about stock market investing for Motley Fool in 1995, but previously I worked aboard cruise ships. I started, the first cruise travel guide on the Internet in New York City in 1999. CruiseMates, one the Web’s top cruise travel guides was acquired by Internet Brands (NASD: INET) in 2006. Once CEO, I am now the editor of CruisematesPaul Motter