I bought a new mattress on Wednesday, and it was delivered today.
It was high time to get a new one, even factoring in all the nights I did not sleep in my own bed over the years (but in a hotel while traveling for work).
My new sleeping pad is a fancy Serta hybrid mattress: layers of memory foam on a base of coiled springs. It is a little firmer than medium*, and I did try it out in the store before I bought it.
*My hotel room in Rotterdam during my recent stay there, had a soft mattress, and it felt as if I was trapped in quicksand.