Hi steelwindmachine,
Welcome to the site
I’m not sure what you’ve read since you found the site but just in case you haven’t read it yet … the best place to start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that can help you make the best possible choice … and perhaps more importantly know how and why to avoid the worst ones.
Two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you.
There is more about the pros and cons of a two sided mattress in post #3 here. Having comfort layers on both sides of a mattress can certainly extend the useful life of a mattress (assuming you rotate and flip it on a regular basis) compared to the same mattress with the same comfort layers on only one side of the mattress. Having said that … if you are comparing two different mattresses that have different designs and use different materials and components in the support and comfort layers then some one sided mattresses may also last longer than some two sided mattresses depending on the quality and durability of the materials and components in each of the two mattresses you are comparing so this would only apply to two mattresses where the only difference between them was that one of them had an additional comfort layer on the bottom of the mattress.
The better options or possibilities I’m aware of in your immediate area (subject to making sure that they are completely transparent and that any mattress you are considering meet the quality/value guidelines I linked earlier in this reply) are listed in post #2 here. The post also includes a link to the lists for the Monroe Township/Newark, NJ areas and the Trenton/Philadelphia/Wilmington which both have a much wider range of options available.
Phoenix