Hi Jezo,
I understand … and there are many “organic” specialty retailers that sell mattresses where in some cases “organic” can be a “code word” for expensive and cater to a market where people are willing to pay more for similar or in some cases even the same materials from manufacturers or retailers that don’t stress or even promote the organic qualities of their mattresses to the same degree.
The main benefit of a thicker latex mattress (or any mattress that uses similar materials) is that it can be more adaptable for heavier weights and multiple sleeping positions. It will compress from softer to firmer more gradually which means that there is more “range” of compression without the mattress becoming too firm for heavier weights (or parts of the body). A thicker mattress can also be part of a specific design that requires it such as some types of zoning or layering that needs more layers to accomplish the design goal of the mattress. It can even just be a matter of preference rather than “need”.
If you can imagine for example a 2" layer of latex (or any foam material) on the floor you would compress it to it’s maximum and feel much more of the floor (it goes from soft to maximum compressed firmness within the space of a 2" layer) but if you had the same softness of latex in a 6" layer on the floor … it would feel much softer and compress more gradually and to a lesser percentage of its overall thickness and wouldn’t reach the same level of firmness or “bottom out” (which means reaching the maximum level of compression or firmness that a layer or a mattress can effectively achieve).
In the large majority of cases … 8" - 9" of latex is easily enough to include the combination softer layers (or sometimes sections) for pressure relief and firmer layers for support that most people of average or even higher weights would need. In some cases … lighter weights or people that sleep in “flatter” sleeping positions, have slimmer less curvy body types, or who prefer a firmer mattress will do well with even 6" even though there is less “room” to design in different layers in the mattress. People that have much higher body weights or larger body types may choose more than the “average” thickness and may prefer the feel and extra adaptability of say 12" of latex. Thicker mattresses can also use firmer materials because thickness and softness are very related and work together. These are all good questions to ask the manufacturer or retailer of a mattress so they can discuss the differences between the different options they have available in terms that are more specific to the layers they use or options they provide.
Thickness and softness work together and because thicker layers (or mattresses) can have a greater range of compression and are more “adaptable” … it’s also possible to use firmer top layers in a thicker mattress and still have good pressure relief because of the greater range of compression of the thicker mattress which can create a mattress with a firmer “surface feel” but that still provides good pressure relief and adapts well to the body contours.
One other benefit of a thicker mattresses that have multiple layers that can be rearranged or exchanged is that there are more layering combinations possible for changing and fine tuning the performance and feel of the mattress but in many cases this wouldn’t be necessary and in some cases can lead to a level of complexity that can make predicting how the layers interact more difficult (see post #2 here)
So the overall thickness of a mattress that is either “needed” or “preferred” would depend on the combinations of the layers and components that are needed to achieve the design goal of the mattress and provide the PPP (Pressure relief, Posture and alignment, and Personal preferences) that can best match each person and their unique body type, sleeping positions, and preferences.
Stomach sleeping for example is a “flatter” sleeping position and carries more risk of sleeping in a “swayback” position where the hips sink down too far for good spinal alignment so it may need thinner soft layers on top for pressure relief so you reach the firmer support layers more easily which can “stop” the heavier parts of the body from sinking down too far and sleeping out of alignment.
All of them would have pros and cons that may be important for some people (depending on what is most important for them in terms of their “value equation”) but I think for most people the last group of 5 on the list would probably represent the best “value”. I would call each one where the information on their website interests you though (and that was close enough for you to take the trip) because of course I don’t know the specifics of every mattress they make or all their prices. When you call them I would tell them your “criteria” including your budget so that you don’t end up visiting one of the choices that you could know ahead of time didn’t offer anything that would be suitable or would interest you that was inside your budget. I think it’s always important to call and talk with any manufacturer or retailer you are considering before paying them a visit as a matter of course anyway both to get a sense of what to expect when you go there and also because websites are frequently not up to date or don’t have all the basic information you may need to decide whether to go there.
Hope this helps.
Phoenix