I have two teenagers, boy and a girl and we take a twin sized airbed. We have used that airbed at all the values and mods and it fits fine. Now with baggage check fees that adds some cost but depending on the length of your trip, it might be cheaper to bring the airbed vs. a rollaway (which with tax run almost $20 per night).
At Pop, we move the table and chairs by the window and put the airbed up against the same wall as the tv/dresser. I take my own fitted sheet and ask housekeeping for an extra top sheet and blanket and pillow.
Just an idea and one that has worked for us for all 18 of our WDW trips!