I posted this in another thread just now, but it fits here, so I'll repost it:
My personal choice is to always rent a car for the duration of my trip. Yup, that costs more than a towncar service, but has advantages of it own.
Pros of renting a car:
* I go where I want, when I want, and never have to wait for a Disney bus.
* I ALWAYS get a seat - I never stand up on an overcrowded bus full of sweaty, smelly, cranky folks who have spent all day touring the parks in the Florida heat
* I can go from my resort to any other resort for a meal, direct, any time of day or night, without agonizing over Disney transportation options
* I can go off-site for shopping, dining, and my obligatory visit to the Universal parks
* I can make a grocery stop (or 2 or 3 if I choose) on the way from the airport anyplace I want with no time limit
* I don't have to tip the driver, since he's me
* No chance of luggage getting lost or mistreated, since the luggage handler is also me
* I can crank the A/C as high as I want - or simply open the windows if I choose
* I can change the radio station any time I want
Cons of renting a car:
* Costs more than DME, Mears, towncar, or taxi (unless you factor in multiple trips like resort-to-resort or a Universal trip)
* Parking lots are not as close to the gates as the bus stops
* No booze on PI nights (cause my Mom didn't raise no dummies, except for my brother, but that's a different story...)
* I can't sleep on the way back to the hotel at night (the car radio keeps waking me up)
* Can't pawn off the driving on somebody else, it's all me ("Ya mean ya gotta use your hands?! That's like a baby toy!")
* Two words: GET LOST
Conclusion:
I rent. To me the pros outweigh the cons, whether I'm staying on-site or off-site.