We drive to WDW. It honestly depends on which resort we stay at on whether we use our car or Disney transportation.
When staying at the BWV (or Epcot resorts area), we park our car and only drive to DTD and DAK. We walk to Epcot, boat to DHS and the bus to MK.
When staying at a place like SSR, we drive everywhere but to the MK and DTD. We either walk or take the boat to DTD. For the MK, it is just easier to take the Disney bus than parking and taking the ferry. DAK and DHS are
VERY easy to get in and out with your own vehicle. On our summer trip last year, taking our car to the parks was a life saver. We didn't have to wait in the heat for a bus. We hopped in our car and soon the A/C was blowing on us. If you have smaller children/stroller and are traveling in the warmer months and/or peak season, I recommend your own car. Just my opinion.
We stayed at Fort Wilderness one year in a cabin. That place is the worst in regards to logistics on getting around the property. Unless you rent a golf cart (which we ended up doing), you spend most of your time waiting for an internal bus to get to an external bus or to the pool area and boat dock. When we stayed there, we planned our MK days for when we had the golf cart because the boat launch area is only accessible by foot and golf cart, same with the area for Hoop de Doo and Trails End. One day, we drove our car to the front, parked and took the Disney bus to Epcot. All other days, we ended up driving our car to the other parks. I don't know if we'll stay there again.

Jennifer