I've been to Maggiano's a number of times, and I have not been disappointed yet.  The calamari is delicious, as are most of the pastas on the menu.  My biggest complaint is the price.  Even though the food is good, I really don't feel that it justifies the high price tag.  There are a number of basic pastas that you can get for less than $15, but these are bare bones dishes.  While still good, you're going to have to spend $20-$30 per dish if you really want to experience what they really have to offer that makes them great.  The atmosphere at Maggiano's differs between restaurants.  The Maggiano's in Denver has a much more classy, and quiet environment with great ambiance.  The Vegas location is much more noisy, usually overcrowded and the service much more casual.  Here's a few tips; make a reservation online, and in the comment box request a booth.