If you have a guest bed, you could consider layering your quilts on top of the bed, perhaps covered by the spread, etc. to keep any unwanted visitors off them, and also to keep them protected from light. If you have an art quilt, you will not likely want to be washing it, but you can vacuum it carefully by putting an old nylon stocking over the end of the upholstery attachment for your vacuum. This will help get dust out of the quilt. You can store this under a bed, etc. Just because they are under the bed, you must not forget them.
Some people make cloth drawstring duffle-type bags to store their quilts in.
You can put a zipped or buttoned pocket on the outside or a label with all the information on the quilt for when you are going to send it off to a show. Of course you must not just forget to refold in different directions periodically so you don't get those heavy fold lines in it. Also, if you are folding, you can save up your leftover batting and make nice little sausages to put in the fold lines of the quilt to help keep them softer folds. Old fabric - If you cannot sell it, there are many worthwhile charities that are making charity quilts and they really appreciate any fabric you can give. Another good use is to make some easy strip pieced quilts that can be washed, etc.