If you don't think they will be comfortable sharing a full-size bed (which, as others have said, is the size of the murphy/innova bed in the renovated Pop rooms -- it's the same size as the beds that are currently in the rooms) you can always take an air mattress (or have one shipped to the room before you arrive). Our
Walmart currently has a basic twin size air mattress for $7. While we haven't seen a completed room yet, I'm guessing there will be space somewhere on the floor for a twin mattress at night.
And I agree with the others who have said that of the 3 beds in the AoA suites, the muphy bed is the most comfortable -- and is very comfortable even when not comparing it to the other beds in the room. It's a standard size 8" thick mattress. The sofa bed was the least comfortable of the 3 but I've slept on much worse. My teen/adult kids who have slept on the sofa bed haven't complained about it (but were pretty vocal about the sofa bed being very uncomfortable in the hotels we stayed at on the drive down and home). And the queen bed is ungodly firm (IMO) and uncomfortable. I was sore and bruised from sleeping on it just one night. Now the first thing I do when we walk in to our suite at AoA is to call Mousekeeping and request extra blankets so I can make a mattress topper for the queen bed. On one of our trips our Mousekeeper noticed what I had done and actually remade the bed to put the blankets under the sheet. I'm hoping they don't use those same mattresses at Pop Century.