Hi mellieinkc,
The first place I would start your research (in case you haven’t read it yet) is the tutorial post here which has all the basic information, steps, and guidelines that you will need to make the best possible choices … and avoid the worst ones.
If you mean the Tempurpedic Simplicity line then I would avoid them completely because they use some of the lowest quality memory foam in the industry that would normally only be found in some of the lowest quality (and price) memory foam mattresses in the market. They don’t meet the minimum quality/density guidelines in post #10 here I would suggest using if you are considering a memory foam mattress. You can read more about them in post # 14 here.
A mattress is only as good as its construction and the quality of the materials inside them and while many of the Tempurpedic mattresses use medium to high quality materials (outside of the Simplicity line) … they are not in the same value range as many other mattresses that use the same or higher quality materials in much lower budget ranges. The name of the manufacturer on the label is not a factor in the quality or value of a mattress.
Outside of testing for PPP using the testing guidelines … the most important part of a mattress purchase is making sure you are dealing with retailers or manufacturers that are transparent about the quality of the materials inside the mattress so you can identify any weak links in a mattress and make more meaningful comparisons with other mattresses. Higher quality sleep shops (whether they are mom and pop or not) and many smaller manufacturers tend to be much more transparent about their materials, have much more knowledge and experienced staff, and much better service and value than most of the larger manufacturers and stores that dominate the mainstream industry.
Some of the better options and possibilities I’m aware of in the Kansas City area are listed in post #2 here.
Phoenix