Hi luvmywife,
Just in case you haven’t read it yet … the first place I would start your research is the mattress shopping tutorial here which has all the basic information, steps, and guidelines that you will need to know how to make the best possible choices … and know how and why to avoid the worst ones. One of the links there is this article about the types of manufacturers or retailers that I would look for.
St George, UT is one of the few areas in the country where there isn’t a list of some of the better options or possibilities I’m aware of (the closest list is for Henderson/Las Vegas here) so time permitting over the course of the next few days I’ll take a look in the area to see If I can help you (and others that may come here that are in the same area) identify some of the better “possibilities” that are close to you.
Phoenix