Hi kmz7,
Outside of testing for PPP to make sure the mattress is a good match for you … the most important part of making an informed choice is to make sure you know the details of all the layers and components in the mattress and in most cases the major brands won’t supply this (mostly because the quality/density of the materials is lower than smaller manufacturers).
Some of the better options and possibilities I’m aware of in the Philadelphia area are listed in post #4 here.
I wouldn’t eliminate any type of material or component (outside of memory foam which you already know you don’t like) because the type of components and materials in a mattress is a matter of personal preference. All support cores (polyfoam, innersprings, andlatex) have softer and firmer versions and all comfort materials (polyfoam, latex, memory foam, microcoils, and others) have softer and firmer versions as well depending on the ovrall design of the mattress. The key is to make sure that the mattress is a good match for you in terms of PPP and that the comfort layers in particular are good quality and durable (a mattress will tend to soften, compress, and break down from the top down) so that you have a reasonable expectation of buying a mattress that has no weak links and will last you many years.
Your budget is plenty to buy a good quality, durable, and suitable mattress … especially in a full size. The steps, information, and guidelines in the tutorial post here will help you make the best possible choice.
Phoenix