Thanks everyone! I think we're going the Costco route, for their return policy. Our current mattress is only 4-5 years old, and it's awful. There are two people shaped canyons in it, and that started happening about 2 years ago. Unfortunately, it was purchased at some bargain basement closeout place due to limited funds at the time, so it had no warranty or any other recourse. So a good return policy is number one this time around.
Too bad, purchasing at Ikea would have meant another trip to Disney..

You can't drive 2 hours to Orlando and NOT go.. I mean, really..