I guess my advice will have to be taken with a grain of salt since 1) We have only had 3 trips (2003, 2009, 2011) and 2) we always have a car because we drive down
Even though we had a car...we always used buses to the parks (we stayed AKL and CBR so transportation was all bus-no boats, monorail, etc.)
Taking the buses to the parks was just easier for us...we never had any delay problems...my son thought this was neat (like an extra ride

). I like to walk to the bus stop, take the bus, and then just be walking distance to the front gate of the park.
Another plus, the buses were usually nice and cold whereas our car would have to get the a/c going
Car would involve extra walking and time: get to resort parking lot which is always farther than bus stops, load our son into a car seat, park, unload kid from car seat, then walk a distance or take a tram to entrance
We did like driving to other resorts for meals. (I made the mistake last trip of using Disney transport to get from CBR to Cape May clambake and it really clouded my experience of the meal)
I saw that someone said they preferred driving to DTD...well, that was actually a total nightmare for us. There was NO parking there the night we decided to have dinner there. We circled the parking lot for soooo long that even a slow bus would have been better.
ETA: Another reason to take my advice with a grain of salt...I never leave a park at closing or right after a parade or fireworks. We don't care for parads or fireworks, and we don't need to close the park. So I should add that our great bus experience is in the morning and afternoon.