Skip all the pillow top and memory foam mattresses and get a Sleep Number bed.  Got rid of memory foam, pillow top mattress after just 2 years because I woke up every morning with sore shoulders.  First night on Sleep Number bed and it was all gone.  Best sleep since my old water bed.  Wife and I have different numbers.  Get the cheapest ones, as they start to add foam and pillow tops to the pricier  sleep number beds and take away all the benefit of the air mattress.  Plus, I think they give you 90 days trial.