Sleeping on air is gaining in popularity. Absent metal coils and springs, air beds use air chambers to control firmness by letting air in or out. Cheaper models have manual adjustments while more expensive models offer a host of features, including motorized air intake and infinitely adjustable firmness.
Perhaps one of the best features of air is that most bed sizes include dual air chambers, making it easy for each sleeper to adjust the air fill to just the right firmness.
Budget-friendly air beds like AeroBed can be quite comfortable, yet may be prone to damage, since air chambers are not protected by any covering other than sheets.
Higher quality air beds such as Select Comfort have air chambers completely enclosed within layers of foam, thus keeping them safe from damage inside a shell that looks like a regular mattress. These also offer up to a 20-year warranty.
Bottom line: Budget versions that completely collapse may be just right for occasional guests. For daily use, however, go with an airbed that looks like a regular mattress and comes with dual chambers. Check warranties and construction features as well.