Hi bmorgan,
As you can see in the guidelines here … I would tend to avoid the major chain stores completely because with their lack of transparency the time you spend there will be mostly wasted because for the most part you won’t be able to find out the information you need to make an informed choice or make meaningful comparisons between mattresses (see this article).
There is more about the different ways that one mattress can “match” another one in post #9 here.
While there would be many hundreds of mattresses in the industry that use materials and components that would be just as or more durable than the materials and components in the Tempurpedic … because they don’t disclose the specifics of the materials and components in their mattresses you won’t be able to make any meaningful comparisons based on comparing specs.
In terms of comfort and PPP (Posture and alignment, Pressure relief, and Personal preferences) … unless a manufacturer makes a mattress that is designed to closely approximate another mattress and it says so in their description (and I don’t know of any other manufacturers that make a mattress that is specifically designed to approximate the Tempurpedic Flex Supreme) … the only way to know how two mattresses compare to each other would be based on your own personal testing or experience.
I would avoid the “name brand” mattresses completely because they tend to use lower quality and less durable materials in their comfort layers that can soften and break down prematurely and would be a weak link in the mattress.
The better options or possibilities I’m aware of in and around Salt Lake City (subject to the quality/value guidelines here) are listed in post #2 here.
Phoenix