Plus, offsite shuttles to the parks can be really unreliable ... and sporadic. Unless I were staying ONsite, I would never want to be without a car.
Agree. We drive to Disney World so always have our own car when staying offsite (and onsite). This last trip, we recommended the offsite place we were staying at to friends whose daughter was going to be there for a quick trip. We were asked to get detailed free shuttle info from the hotel to the parks. So we did and my husband came back and told our friends that their daughter should rent a car. The hotel was a mile from Disney property and the shuttles went to the TTC and Epcot twice in the morning and came back from each place twice at night. The only rope drop anyone was going to make was Epcot right at 9:00 AM. And if anyone wanted to stay at a park for the nighttime stuff, they would have to take the last shuttle at 11:00 PM. From the TTC. There were NO afternoon shuttles available at all.
So PLEASE ask your offsite resort to email you a copy of their current shuttle schedule.