Problem: You don't have a spare bedroom.

Solution: You can invest in an inflatable air mattress, but most air beds are still made of vinyl, which can be punctured by a stray safety pin or a cat's claw. Look for models with thicker padded tops (like the AeroBed Premier Pillowtop, $180 for full, www.thinkaero.com), or cover the bed with a mattress pad to provide a protective layer of cushioning.

A simpler solution? A feather bed (like the Pacific Coast CuddleSoft Feather Bed, $109 for full, www.pacificcoast.com). “It can be rolled up tight for easy storage, and the extra layer of cushioning makes the couch—or the floor—that much more comfortable,” says Meryl Starr, author of The Home Organizing Workbook: Clearing Your Clutter, Step by Step (Chronicle Books, $25, www.amazon.com).

Finally, instead of tossing out an old mattress, consider storing it under your bed (if space allows) so you can just slide it out when guests arrive.

Tip: Look for zippered allergen-proof pillow-cases ($5 and up, www.natlallergy.com). "They reduce exposure to dust mites, which are one of the most common allergens," says James Seltzer, an allergist in Oceanside, California.