Mattresses, what’s your recommendation and why?

Growing up I could sleep on most anything, anywhere. My favorite is a cot in a sleeping bag. Since that's not an option in my current RV I would prefer a mattress that keeps the DW and I comfortable all night long. Heck, in the early years of our relationship we fell asleep on the 9th fairway and did not wake up until it was almost too late! Thank goodness it was not the 1st fairway!