I don't really know Summer Bay, other than having driven by it many times and reading what I've read at the timeshare users group site, but I believe that there's a lot more to do at Vistana than there is at Summer Bay. People tend to speak very highly of the Houses at Summer Bay, not quite as highly of the other parts of the resort. Vistana is large and well situated for more of the theme park area of Orlando than is Summer Bay but both are quite close to Disney property (Vistana is near Downtown Disney/Epcot/Boardwalk/Hollywood Studios; Summer Bay is near Animal Kingdom). We've stayed at the Vistana Resort at least a couple of times and liked it quite a bit. We like staying in that general part of area so have tended to find resorts in that area that are to our liking and tend to go back to those. The older phases of Vistana have pretty large villas (larger the better, I think, for staying two weeks!!). Lots of pools, usually lots of other kids around the ages of your's if they're so inclined to make friends quickly. And great location - a couple of miles to I-4, 6 to 8 miles to the Disney parks' parking lots, maybe five mile to SeaWorld and 8 or 9 miles to Universal.
Dick Taylor