I had a removable topper before we purchased our present pillow-top mattress, and although it was much more comfortable than the mattress alone, the thing used to shift around and drive me crazy. But...ymmv. :)

I purchased a Stearns and Foster firm mattress with a layer of memory foam on the top (not a pillow top, though). It gives me a lot of support for my back and just enough memory foam so I don't sink in it.

The advantage of going with the topper is that you can change it later. Want a softer feel? Get a softer topper instead of replacing your entire mattress. Want firmer? Ditto.

You also get more "deep support" going firm + topper vs going plush. That's not necessarily better, but some prefer that sort of feel.

Also you can go with a cheaper mattress, since the feel of it will be based on the topper more so than the mattress itself.

Never posted on this forum, usually I'm over in Kitchens. But I just had to give you my 2 cents. We had a memory foam mattress, it ended up being returned after about 20 months. The depressions were horrible. Also, the foam didn't breathe, and we were so hot at night. We ended up going to the Sealy Spring Free latex mattress. It is the best thing we could have done. It was more money, but it really is fantastic. We aren't hot anymore, it supports you in the places where you need it. I highly recommend it.

The most important piece of advice I read while mattress shopping was to remember that the mattress is NOT a luxury item. It is utilitarian, it is meant to serve a purpose. You can make it look luxurious by adding your bedding to it, but it's purpose is to help you get a good night's sleep and wake up with no back pain! This is why we didn't go for a pillow top or anything that was so soft and "luxurious".

I found a lot of good information on this website. Even though the guy who writes it sells mattresses, he is so honest in his answers. And it seems as much as he would love to sell a mattress to you, he wants consumers to be informed and really doesn't seem to mind if you are buying elsewhere. So check it out.

Good luck!

Here is a link that might be useful: Mattress blog

Thanks for everyones input. I thought I'd follow up and let you guys know what I decided to get after all my research. I bought a offset coil regency mattress set from the Original Mattress Factory for $620. Then I bought a 3 inch 32ILD talalay latex topper from The Foam Factory for $230. And then I bought a high loft mattress pad from overstock.com for $40.

I think I came out really good on this one...both the latex topper and mattress have a 10yr non prorated warranty.

I think you made the right decision. I did the same thing in January as I bought a firm Sterns and Foster mattress and then got a 2" memory foam topper. So far I love it. Should be much easier to replace the memory foam topper than having to replace the mattress.