Hi cn1ght,
Hopefully you were reading the mattress shopping tutorial here and not all the pages on the main site
The better options and possibilities I’m aware of in the Cleveland/Akron areas (subject to following all the steps in the tutorial post of course) are listed in post #2 here.
The support core of a mattress would be the layers that are deeper inside the mattress (say the bottom 6" or so) and are firmer layers that are meant to prevent the heavier parts of the body from sinking down too much. I doubt that the mattresses you tested had 6" of memory foam in the bottom layers (it’s not likely that any manufacturer would make a mattress like that) and it’s much more likely that you were given incorrect information and that the bottom 6" was polyfoam not memory foam.
It’s accurate that side sleepers generally need thicker/softer comfort layers to relieve pressure points but I would avoid thinking in terms of the specific number of inches of a single layer because every layer will affect every other layer to some degree so a mattress with a 2" top layer with a softer layer below it may be closely equivalent to a mattress with a 3" top layer of the same firmness with a firmer layer below it. I would use your actual testing to decide whether a mattress is a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). Your question is similar to an earlier one today and my reply in post #2 here would also be worth reading.
You can read more about box springs, foundations, platform beds, and other support surfaces that are suitable for different types of mattresses in the foundation post here and the two posts it links to. While the floor would provide a good support surface for any mattresses that needed firm non flexing support (which would include most mattresses with a foam support core) … you would have a very low sleeping surface which may be uncomfortable getting in and out of bed and there would also be little to no ventilation under the mattress which could increase the risk of dust mites, mold, and mildew (see post #10 here) and possibly stains on the mattress which would void your warranty.
The Captcha I use is one of those “necessary evils” unfortunately. It’s by far the most successful Captcha I’ve ever used to keep spammers out of the forum and not a single automated spambot has been able to register and spam the forum since I’ve used it and with other Captchas (which used images with letters in them for the most part) there were some days where a dozen or more automated spammers made it through. I realize it can be frustrating sometimes (although the “game” can be refreshed) and the ads are what support the free software and they can be somewhat annoying as well but overall it’s the best I’ve seen and it solved a significant issue with spam on the forum.
Phoenix