I totally understand where you are coming from. We are still a family of 4, but a 15 year old girl and almost 18 year old son makes staying in one room hard. Our next trip, I am also thinking about two rooms. The Poly is our favorite resort by far and will really miss the balcony/patio.
That's our problem for our January trip. My DD are 18 & 21 but don't share beds well. The younger one always slept on the daybed at the Polynesian.
We haven't gone as a family in 3 years, staying at the Boardwalk CL(regular sold out) and wondering if the room and daybed will be big enough.
Other option is staying 2 rooms at POR with s/p/d package for a little more money. I keep going back and forth!