Hi Terry,
The first place I would start your research is the tutorial post here which has all the basic information, steps, and guidelines you will need to make the best possible choices … and know how and why to avoid the worst ones (which would include the major brands such as Serta or any mattress where you aren’t able to find out the quality of the materials inside it).
I’m not sure where you are exactly but in your more immediate area the only option I’m aware of that I would consider would be the Restonic mattresses at http://www.ivansmith.com/ but only if they are a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) and if you can confirm the quality of the materials inside the mattress you are considering (see this article) so you can make sure that there are no weak links in the mattress (see post #4 here) and make more meaningful comparisons with other mattresses.
Post #4 here includes some possibilities in the Shreveport area and post #2 here includes some possibilities in the Jackson, MS area. With any of these “possibilities” you will need to confirm you can find out the quality of the materials in any of the mattresses you are considering.
A little further away post #4 here has the possibilities I’m aware of in the New Orleans area and post #191 here includes some better options yet in the Baton Rouge area and post #4 here is for the Dallas/Ft Worth area and may be the best option of all.
The tutorial post also includes links to the better online options I’m aware of if you are comfortable with an online purchase.
Phoenix