So I'm looking at buying a house and I already have friends who are ready to come visit once I get moved in. Problem: I won't have a guest bedroom. So I'm stuck deciding between if I want to buy a futon, sofa bed, or an air mattress. I don't think I can afford a NICE sofa bed unless I find one used off craigslist, so I'm thinking there's probably little difference between cheap sofa bed and cheap futon. But at that point, I'm wondering if I should just buy a nicer air mattress? I mean... sleeping on the floor on an air mattress would probably be just as comfortable as some of the cheaper, crappier futons out there... Thoughts?