When we immigrated in 1999, one of the first things we did was buy a mattress from Everest Mattress. We had closed on our new home 4 weeks before all our things arrived by sea from Europe, and wanted to be out of the hotel and onto our new home. 13 years later, after returning to WA after living in CA, we are about to start shopping for a new mattress.
We had bought the Elite Luxury Firm, and it had a 20-year warranty back then (looks like they are down to 10 years now). It has held up really well; we are both around 200 lbs, and we are often "energetic" in bed, and the bed is still in great shape, but after 13 years any bed is going to start getting a little tired. However, it will be just fine for the guest bedroom, and we expect it to keep going there for many more years.
Just as when we first arrived to start living our American dream, buying a mattress seems very confusing, but it's as clear now as then that prices of the big brands are inflated, and not a useful guide to quality, and after some research we've decided to go back for more of what we know.