Foam mattresses are available in latex (rubber) and polyurethane. You may prefer the feel of one or the other, but polyurethane usually lasts longer. Also, higher density foams are longer wearing than those of lower density. You can select a soft, medium, or firm mattress (the choice has nothing to do with density).
Maintain a foam mattress as you would any other. Protect it with a quilted mattress pad and air it when you change the bedding. Vacuum the cover occasionally, and if it is removable, launder it about every 6 months. Foam mattresses need not be turned.
To spot clean a foam mattress, use a dry-foam cleaner or a sponge dipped in detergent solution and squeezed dry; allow the bed to dry completely before making it. Note: solvent-based cleaners and heat deteriorate rubber.