The Tempur Base is amazing too and you could maybe incorporate it into your existing bed. The Tempur Mattress is sec one to none and is the leader in Memory Foam technologies. Since i bought mine there is now 3 different mattresses but i have the original and its as good today as it was when i bought it 10 years ago. You are fully supported in the optimum position and no point load weight. I rate it very highly.
http://au.tempur.com/mattresses/