I am here right now and we are staying at a rental house for the 3rd time. (not the same house.....3 different houses). We have found all of them on VRBO.com. The first one we stayed in was the Disney Theme House which is pricey but so fun!!! We were close enough to walk but ended up driving each day because we had to walk around the DL Hotel which was a long walk, but do-able (and very tiring after a day in the park!).
The 2nd home we stayed in was a little smaller and we had 11 people squeezed into it. It would have been fine for a smaller family.
The one we are in now is perfect for us! We have 13 this time and there is enough room for us to spread out. This one was on ultimatesocalvacationhomes.com and it is the Garden Retreat.
Read though the reviews of the homes thoroughly on VRBO. Sometimes on VRBO the home owners will also have a separate link for the homes specific website which gives a little more information.