Ditto what Rex said, we did 4 in a 1 bedroom at VWL, my kids are ages 12 and 4, that was tight, a reall cramp always folding and unfolding the sofa bed, and waiting on the 12 year old in the shower!!! I'm waiting for more points to do an add-on, so we will always be able to do a 2 bedroom for extended stays. 4 nights in the 1 bedroom was enough, any longer, we would definately want the 2 bedroom.
the cabins are a great alternative, they do sleep six, it is cozy, but it works. Put the kids in the room, and the parents can sleep on the Murphy bed.