Well We just tried out a mattress that will be delivered Monday am. It's the Serta Natural Response firm. The last mattress we got was a Spring Air and it's only 6 yrs old but totally hate it. IT started sagging right away. We have another much older Spring Air back Supporter that we loved and is now in the guest room. Our visitors rave about it. the only reason we bought the newer spring air was that we went from a queen to a king.
My son and DIL bought the Natural response and said they sleep all thru the night. But they are young so i hope this one tuns out to be good. I'll keep you posted. BTW, it cost us $1900.