My wife is 5ft 4inch, weight, 9st 4lb, I am 6ft 1inch, 16-17 stone, there is quite a difference in body builds for a king size mattress. I have suffered with nigling back pain for a while. I also have a disc problem with my lower back, which can happen once or twice every two years. My wife does not suffer from back problems. What type of mattress would you recommend, we have a solid wood base bed.