Just last year I bought a Stearns & Foster (their mid-to-upper line, not the cheapest) and am overall pleased with it for the price I paid. One of the reasons why I went with S&F is because of their incredible warranty -- if even the handles on the mattress break/rip off, they replace your mattress (not repair it).
Most mattresses you only rotate, not flip. Mine is one you rotate and it has handles on all 4 sides of the mattress, it is SO easy to rotate that we do it every 2 months.
I would advise against getting a full pillowtop since the top wears out so fast. I would get just the "plush" if you are wanting something soft, and of course if you need a more firm mattress get something firmer.
If I had unlimited funds, I would get an upper-line Tempurpedic. Their lowest line isn't that great I don't think, but the higher end of their line is great.
Edited to Add: I just thought to add that having foam around the outer edges of the mattress is VERY important if you get a spring/coil mattress. It helps the mattress keep its shape as well as make it comfortable for those who sleep on the edge of their bed or sit on the edge. I have it, and now I don't know how I lived without it!
In Consumer Reports, Tempurpedic is rated the #1 brand by consumers (CR doesn't test any mattresses themselves, they compile only from consumer reviews so I don't know how accurate it really is). Simmons is #3 I believe, Serta down quite a bit further.