Hi gu_obos,
That’s a ton of excellent info. I’m sure Phoenix and others will offer a number of excellent suggestions too. For starters, make sure you’ve read the first post on how to evaluate a mattress. It sounds like you have, but in case not:
Second, Phoenix just wrote this in another thread, and to quote him:
"Pressure relief and “comfort” is what you tend to feel when you first lie on a mattress and this comes mostly from the upper layers.
Support and alignment is what you tend to feel when you wake up in the morning either with or without back pain or discomfort. This is where the deeper layers can have a more significant effect.
Durability is all about how you feel on a mattress in a year or more down the road when lower quality materials have softened more rapidly."
I write that because you are shopping and experimenting, and so to determine which mattress is most suitable and will work for you, given 2 that haven’t worked, it’s important to determine if it’s been the support layers (seemingly less likely) or the comfort top layers which provide comfort and pressure relief.
Also, as Phoenix has often wrote, it is much easier to soften a mattress that’s too firm than to firm up a mattress that’s too soft. That’s largely because you can add a ‘topper’ (which is essentially a pillow top, as you considered- you can tell your wife not to slap you, it’s an excellent idea and the very purpose for adding them). Before deciding on a topper, which is all about adjusting the comfort layer, one needs to make sure that it’s actually the comfort layer that needs improvement, and not something about the support layer.
There are toppers in all varieties, ranging from value budget to premium pricing. They’re made of basically all the same materials you’d find in a mattress comfort layer, the common being memory foam, latex, polyfoam, wool, cotton, silk, gel, buckling gel, feathers, down, and no doubt others, all in a variety of thicknesses and firmness levels. They come both finished and unfinished (I.e. With fabric encasing them or not).
Others will no doubt comment on other questions you have.