Oh yeah, I only wanted to fly in one just to see it once and could say I flew in one.  Otherwise they're pretty much the same.  In fact, the newer models are probably nicer, and quieter.

The actual seating configurations are what I care most about (seat arrangement and legroom).  Getting a window-aisle pair on a wide-body 2-4-2 or 2-5-2 config is a must for my tastes.  The MD-80 or 90's are great as smaller planes too with the 2-2 or 2-3 seating config.