even when we used to drive down and have a car. we LOVE the disney transportation. we love not worrying about directions, getting lost, and being able to have a few drinks.
that being said, since we like to break up our day with pool time in the middle, we did like to drive to either DHS or AK in the mroning. it was much quicker, and those are easy parkd to get to.. but we would still take the bus in the afternon or evening.
water parks? drive if you can,.
downtown disney? if you are jsut going for a lunch or shopping, and a quick grocery/beer stop at the Hess, drive. if you can.. the DTD bus goes a weird LONG way around. but if you are enjoying an evening of cocktails, the bus is great!
and remember, there is a very good chance you might have to stand on the bus. (happens all the time on public transportation in big cities, like Chicago.) Dont' get on a standing room only bus and expect someone else to get up off their seat for you. if you need to sit, wait for the next bus. many of us will get up if we can. some have problems you can't see and don't know about.. and we are all tired, of course. also, you don't know that we didn't wait for another bus to ensure we could have a seat.
if your party NEEDS to sit, then drive or get a cab. On disney transportation, you are guaranteed a ride, not a seat.some people, after discovering this. opt to rent a car if they flew to WDW. only you can take total care of your families' needs.
I think it's great that you can get all over WDW without driving, if you need to.