Try and get the salesperson to include a mattress pad for your new mattress. The memory foam mattresses (heaven for bad hips) will eventually form a body shape in them, and the foam 'packs' down in those areas that are used more. One little spot on the mattress from any type of body fluid/ lotion/ food, etc. and the warranty is gone. It is highly recommended the mattresses be covered with a high quality pad. We ended up cutting a slit on one long and one short side of our memory foam top (it is Simmons Beautyrest and the top is sewn separate from the thick foam underneath on the mattress top.) We shake the foam top (about 4" of tough dense foam) and put the sheet back on and it is good as new for a couple days. We decided to cut the mattress topper part of the mattress top as the warranty was void anyway after our GD took a nap in NanaPapa's bed while the mattress pad was in the wash. UGH. Could have had a free mattress top replacement. Best of luck in finding just the right mattress for your comfort.