Depends on what type of people you are.
I tell everyone to rent the car for the convience factor. You can visit Publix, stock a cooler, and drive to SWF. It also depends on how long you are staying. You will pay $7 a day to park at the hotel, plus gas, plus the rental charge. But, you can go anywhere, anytime.
On the other hand, most limo services will make one stop as a perk for using them, so you could still stock that cooler before check-in. Most people from Disney are used to not renting a car, so it's kinda hard to explain the convience thing to them.