Every couple of months sprinkle a mixture of baking soda and a tablespoon of your favorite fabric softener (powdered I assume) over your mattress, let it sit for an hour, and then vacuum it up. Gets rid of dust mites and freshens up the mattress. Keep that same mixture in a small mason jar with holes poked in the top in your linen or clothes closet to keep it smelling fresh!
ONLY use this and it leaves floor spotless. (Heavy duty floor cleaner recipe: cup white vinegar 1 tablespoon liquid dish soap cup baking soda 2 gallons tap water, very warm.) It leaves everything smelling amazing.