Well, our expensive mattress really is the pits (literally), so I would NOT recommend a Serta Sleep-Aire. I wish I'd had done my research before buying this one. The first 6 months were like sleeping on a cloud -- so comfortable. Now we have peaks and valleys, and back pain! $1300 down the drain.
From the research I've done and the mattresses I've laid on (including the sleep number), here are my conclusions to help you with your search:
#1 -- DO NOT get a pillow-top mattress. They feel good for a few months, but the material breaks down on the pillow top and they don't last. You can't flip them, either.
#2 -- Unless you and your DH have different mattress preferences as far as softness and firmness go, you do not need to blow a bunch of money on a sleep number mattress. They are great for that purpose (different mattress feel), but if that's not an issue, save your money.
#3 -- Tempurpedic is good, but people complain they sleep hot in the summer.
#3 -- Go with a good quality inner spring coil mattress without a pillow top, but possibly with a latex topper that you purchase separately. At least the topper can be replaced in a few years, unlike a pillow mattress, and if it gets too hot in the summer, you can take it off. The latex is supposed to be better though to help with the heat issue.
Here's a link to a good mattress forum that might help you out:
http://www.whatsthebest-mattress.com/forum/