Our mattress is about 10 yrs old. It was not cheap! I do not find it overly comfortable. DH is better about it but then again, he's like a horse and can sleep standing up! We are both leaning towards the sleep number when we replace this. I, too, like a softer mattress than DH.
Be careful about the height of the box spring as well. Our mattress (22" thick - read very expensive sheets! /box spring) are so tall that we both need to climb into bed! DH is almost 6' tall! At the time, half-height box springs were available but we were clueless. And since they have the set ups so low in the stores, you would never really notice.