My husband & I bought a top of the line pillowtop Serta Exploration, and within a month we were both sagging into ditches with a mountain between us. Unbelievably, it has gotten worse over the 1.5 years since we bought it! He's @ 200lbs and I'm @ 130lbs and we're both @ 5'6". We hate this mattress and will never buy another Serta. My "leg ditch" is less deep than my "torso ditch, " and when I sleep on my side, (legs stacked) my knees actually hurt from being torqued upwards when I wake up. Same issue applies for stomach sleeping. Worse than sleeping in an army cot. Consider yourself warned. read full review »