Just wanted to say if someone is using their RCI for a DVC exchange there may not be availability at your preferred DVC resort, therefore I'd look into the possiblity, which is most likely, of being at Old Key West or Saratoga Springs. They are both beautiful resorts, with OKW having the most spacious rooms in the larger accommodations. Transportation would be by bus to all the parks.
I can certainly vouch for OKW as being a very nice resort! My mother and I stayed there a few years back, and were very happy there. Most of the buildings don't have lifts, so you'd need to request a ground floor room for medical reasons (include that last bit, as it gives you priority over those who would just like to be on the ground floor). It is a fairly spread out resort, but the room we were in was close enough to the main building to be an easy roll.
As
DCL said, the rooms are very spacious, and we had loads of room to get my wheelchair in, and move about in it. My only concern is that the beds in the standard rooms are very high, about 3' I reckon. It was a bit of a clamber for me to get into bed at night with aching joints, and I'm about 5'4". I'm guessing the beds in wheelchair accessible rooms will be lower (I'm partially mobile, so we were in a standard room) to aid transfer, but I can't swear to it.
The swimming pools have bump steps (well, the one we were close to did, anyway) and the main building has power assisted doors most of the places where you might need them. We didn't have any problems with the buses when we were there (it was September, so fairly quiet), and I got on the first available bus almost every time.
If you were looking at non-DVC hotels too, POFQ is a nice small hotel, and is very easy to get around.
EDIT: Just wanted to add a few things that I didn't get time to write yesterday. French Quarter is a good resort for people with limited mobility, as everything is close to everthing else. I'm pretty sure the pool has bump steps (please someone correct me if I'm wrong), and the main buildings are easy enough to navigate on wheels. Last time I stayed there was before I needed a wheelchair of my own, so I was using a heavy WDW rental with untrained arms, and I could get myself about the hotel when I needed to. With my lightweight chair and big muscley arms

, it would be a doddle!