For the price of a car service, you can probably almost rent a car for the week. We were not going to rent a car for our January trip and literally decided the night before to rent a car LOL!!
As Lori said, it is very nice for when you need to go to another resort. To get from one resort to another, you have to transfer at either a theme park or at Downtown Disney. It can take as little as 40 minutes, but in a worst case scenario (just missing each bus), it can take over an hour.
We also use a AAA diamond parking pass, which helps immensely in most parks (not so much at the MK).
Interesting. The only park I would have thought it was worth it would be the MK so that you don't have to rely on the parking tram. The MK is the only part where we generally ride the tram.
Beth, mom to older DD (8/01) and younger DD (10/06) and always missing Leah (4/22 - 5/1/05)