We are a family of four and so far have only done studios - at OKW, SSR and VWL. There are things about each one that we like over others. Our boys are 9 and 10 and they do NOT sleep well together, so we usually sleep one adult / one child -- so my preference is for OKW for sleeping.
However, what I like about the studios at SSR and VWL are that the bathroom vanity area is outside the shower / toilet so I can brush my teeth and wash my face while someone else is using the facilities -- makes getting ready in the morning (or more importantly at night after a long day in the park) a bit more efficient. I also like the lighting in the vanity / closet / kitchenette area better at SSR and VWL than in OKW - it seems darker and also less room in that area, so if you're using the kitchenette, that's something to consider as well.
Additionally, we enjoy sitting out on the balcony - so we like SSR better than OKW because it's a bit more spacious - and all four of us can be on the balcony at once. We only had a first floor room at VWL, so we didn't use the patio - and I've since learned to request a "non-1st-floor" room
Again, at OKW the boys really like the pool / slide there (although they also like it at the other resorts) but they REALLY like Community Hall at OKW - air hockey, pool, games, etc. But they are 9 and 10
I've slept with DS (10) on the pull-outs and they are fine, and if the boys slept together, they would be ok on the pull-outs, too -- and it is nice to have the little couch to sit on to watch t.v. instead of having to sit on the bed.