Hi Primetime,
The Los Angeles list is in post #2 here.
I would suggest some preliminary phone calls first to describe the general type of mattress you are looking for. I never visit any outlet … even if they are right next door … until I have talked to them first to get a sense of what they offer and the level of service and knowledge of the outlet. Half an hour on the phone can save you a hours of testing time. For example you would be looking for memory foam that was on the cooler side of the memory foam range if you are committed to the feel of the actual material itself rather than just liking a particular mattress (such as the Optimum) but could also be happy on other materials that offered similar pressure relief, support, and preferences of “feel”. This will not only save you a lot of time but will give you a good sense of who to visit that may have mattresses you want to try and what to expect when you go there.
Phoenix