Some of the rooms in Alligator Bayou at Port Orleans have trundle beds and accomadate 5 people.
If your family is 5 people, but it's mom, dad, and 3 kids - if one of the kids is under 3 or 2 (I think) you can all be in one room at a mod or value. I know if the third child is an infant you DEFINITELY can do this.
Hope this helps a bit!