I will share my mattress experiences - We had a queen mattress (simmons) that was replaced under warranty after about 4 yrs due to sagging.. We then moved into a new house and bought a king size (IBC) that is also sagging badly that i probably could be replaced under warranty.. It is not a pillow top, but the next step below that (plush?? - still has a latex topper built in)..
The springs are what provides the support for your back and the toppers are just for your comfort (do you like a harder surface or a softer)
I researched a LOT on mattresses - and here is what I found out..
Tempurpedic - "memory foam" some ppl dont like them because they consider them hot and you can have trouble moving around in them (ie 'swimming in pudding' is one explanation I read).. They also 'gas' badly for weeks (emit noxious fumes).. They should not sag like an IS. I have read that they may not last as long as latex mattresses though..
Inner Springs - today IS mattresses are not the same quality from the 70's.. The springs are either not as heavy OR dont hold their shape as well.. There are about 2 or 3 manufacturers that make inner springs like the 70's that will hold up much longer than a regular IS mattress (i found that on a mattress forum and dont remember the mfg names though)
Latex Foam - If you dont like the memory foam pudding feel, a latex may be an option to consider.. The natural latex will not break down like some of the normal foams used in mattresses.. Typically ppl dont find that they hold heat. also you can get varying densities in layers that can offer firm support, but yet provide comfort to pressure points.
some mattress places will try to sell you a 'latex mattress' but it is just an IS with a latex topper built in.. It will give you the same sagging issues.. I would beware of any manufacturer that doesnt specify the type of foam and its density used in their mattress
I just ordered a 3 layer Natural Dunlop mattress from
Latex Mattress Factory - $595 Latex Mattresses - 100% Natural&Talalay on Monday.. We went a x-firm/firm/medium (top) layers that are zipped up into a mattress cover. With sleepez you can exchange any (all) layers within the first 90 days for something firmer or softer..
Here are some links
good forum for information on mattresses
Mattress Forum
latex mattress vendors
Latex Mattress Factory - $595 Latex Mattresses - 100% Natural&Talalay - highly recommended on a mattress forum
Latex Mattress - FloBeds.com - highly recommended on a mattress forum
All Natural Latex Mattress - recommended on the forum
place to build your own mattress if you are adventurous
Foam Products, Sound Proofing Foams, Seat Cushions, Memory Foam Pillow, Mattress Toppers, Pads
good luck
brian