When you say three adults, what is the relationship there?
We have a family of five, but it's my husband and I and three kids, two of whom are teens. We love staying in AB at POR, but it is really crowded in the room. (We have also stayed at CBR and enjoyed that resort too.) I think all of the deluxes can accommodate five in a standard room except AKL and WL. We have stayed at the Poly and loved it, but I just can't justify paying more than double to stay there when I love POR so much.
However, if it was my husband, me, two kids, and my mom, there is no way I'd want to stay in one room at POR. I have a friend who did the family suites at AoA with her family and her mom, and she felt that even the suite wasn't a great choice. Putting a grandparent in a fold down bed with the kids in the living room doesn't work too well.
If it's a situation like that, the Cabins would work if they don't mind sharing a bath, because parents and kids could be in a room and the other adult would be on the sofa bed. Or, I'd look at off site or staying in two rooms. People always suggest renting points, but I don't like the arrangements for five people even in a one bedroom, and two bedrooms are expensive, even if you rent points.