We always get a car - but there are many people who don't. I think a lot depends on what you plan to do. If you are likely to only need transportation between your hotel and the theme parks the buses may work ok, but we like to convenience of a car. If you are like us and like to hop from park to park, go back to your hotel for a mid day break, and eat breakfast or dinner in another WDW resort a car will work better. The WDW transportation system is very inefficient in getting people from one resort (CBR for example) to another (say the GF). We also like having a car to get to Downtown Disney (again, WDW transportation is not good for this) or the waterparks ( no long rides in a wet bathing suit on a cold bus). Also, after a long day at the theme parks it is nice to get in your own comfortable car for a short drive back to your resort as opposed to waiting 20 minutes to get on a crowded bus. If you have young kids a car has it's benefits. Folding a stroller and getting it on a crowded bus can't be much fun. Just a few thoughts. By the way, a minivan is probably the way to go.
