Serta Perfect Sleeper Pillowtop. It IS the most comfortable bed I've ever slept on! We've had it probably 8-10 years now and it still is a wonderful mattress.
luvdzney, we bought ours at a furniture chain in town called HOM furniture. I had to call around to several furniture stores, and I only found 2 that still carried them, but it was worth it. I absolutely love this bed.