After seeing various "surgery" success stories, I am ready to cut the failing top from our 5yo Serta Perfect Sleeper "Coastal Oaks" and try some DIY replacement options.

My wife (5'8" 140# Back) and I (6'1" 230# Side/Back) liked this mattress until the top totally gave out in the last 6mo or so. This is a fairly firm innerspring with a 4.5" plush top (I know nothing of the actual construction), so I'm hoping that I'll find the coils in good condition and that I can layer some quality foam in place of the failed layer and get several more years of use from the remaining bits.

I'm not sure where to start as far as layers go. Neither of us is a big fan (in the showroom, at least) of the feel of MF, and when we try mattresses out, we tend to gravitate towards about 3" of (indeterminate, probably PU) foam over a firm innerspring. I would like to try some latex options, but aside from the local Verlo, I'm not sure where we could try some out before committing. I tried Googling locally, but mostly found foam vendors selling upholstery materials.

If anyone has some relevant experience or local vendor recommendations to get us headed in the right direction, I'd really appreciate it.

Thanks!