Memory foam and my back don't get along so I replaced my original mattress with a Sleep Number RV Premier Bed - Radius Cut, King. This was almost 5 years ago and it was the best investment I have ever made.
The funny thing is originally my "sleep number" was 45, then 50 felt better for a couple of years and now I'm at 65. Who knows what is down the road, but I can adjust to it - just press the button.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof