I have a Sleep Number bed. I find I get to sleep much faster, and stay asleep, and don't roll around. With my old bed I was waking up several times a night and tossing and turning. So that much is great.
However, I would only recommend it in a King size. The mattress has two chambers, so there's a split down the middle that is relatively unsupported. If you sleep by yourself in the center of the bed, you're sleeping in a canyon. Each chamber of the queen mattress is a bit narrow , I occasionally wind up half on the chamber, and half in the canyon. Since the chambers of a King would be much wider this wouldn't be as much a problem.
Also, you'll probably want to blow the bed up to a higher pressure when you have sex, and then deflate it later when you sleep.
The company's warranty/customer service department is fantastic.