Tempurpedic...you will never go back. I am an unquestioned "cool" sleeper, and it has never bothered me, even with a down comforter. I would however reccomend that if you are concerned, avoid their "Grand, Bella Sona, Celebrity or Rhapsody" lines and go with the classic or original. These others just add more padding on top of the foam and are less comfortable to both my wife and I, as well as being "warmer".
Rumors of sweaty foam are greatly exaggerated.
Bates...your ex weighs more than you do...she would sweat in a meat locker.
In all seriousness, quality of sleep is exceptional. Left to my own devices, I normally sleep about 7 to 7.5 hours on the Tempurpedic to feel comparably rested to a 10-11 hour sleep on a "premium pillow top" mattress. Trouble with the pillow top was that invariably after that long in the bed, I would wake up with stiffness and aches in my back.
Two other huge points. My wife is a night owl...when I am flying we scarcely ever go to bed at the same time and she has never once woken me up getting into, or sleeping in the bed. (Well...at least not unless it was intentional...

) Lastly, the wife and I used to fight over stiff vs.soft mattresses. The tempurpedic is just right for both of us.
Expensive...but worth every penny and then some. PM if you have more specific questions.
<<EDIT>> I believe that Holiday Inn now has Tempurpedic mattresses in their hotels. Not 100% about the chain...but one of the major brands...If you are interested, and don't want to spring for the in home trial, stay at one of their rooms for a few days and see what you think. Fair warning though...give it a few days. The first night or two, while not uncomfortable, take some getting used to.