Hi bedwench,
Some of the better options in the Raleigh/Durham area I’m aware of are in post #6 here. There are certainly some good places to test and possibly even purchase latex in the area (although not everything on the list would be what I call “best value”).
Latex is a great choice for temperature regulation because it is the most breathable of the foam materials but the ticking/quilting materials, mattress protector, and sheets and bedding can also have a big effect on temperature regulation in a mattress as well. There’s more about this in post #16 here.
There are also several ways to accommodate two people who have very different needs and preferences on the same mattress. some of these are discussed in the first part of post #2 here but side to side split layering can be one of the most effective if your testing indicates that most of the “non split” layering you test doesn’t work equally well for both of you (although you may be surprised that some types of layering do work well for both of you).
Good luck in your testing and I’m looking forward to your feedback and any questions you may have along the way,.
Phoenix