well, after air mattresses, futons, and couches, my next best suggestion besides something like a camping pad would be a fold-up twin (if you have only one guest). we had one (from a garage sale) and i know they're sold at mattress stores. the frame folds in half, so it's upright, with wheels so it's easy to move around and takes minimal closet space, for a real bed. after sleeping on it for a while (months), it's not that comfortable because you sink in the middle - although i'm guessing a newer one would be much better for this issue - and it's fine for a few days. google 'folding bed' to see pics/prices.