Mattress Forum

I just found this forum while trying to do research before purchasing a new mattress and thought you all could help. I am going to purchase a King size mattress/box spring. Don't need cheap, but don't want to spend more than I have to either. My big issue is I am retired and spend a great deal of time sitting up in bed, either using my laptop or watching tv. Most people do this in an office or living room, but I do it in bed. So, I spend almost as much time sitting as I do sleeping. Obviously, the mattress develops a good sized divot where my butt is up by the headboard. I don't want a reclining mattress because I sit straighter up usually than those provide and change the angle of my upper body often. I prefer just moving the pillows I use to recline on. So, I need a mattress with very good durable support, yet soft enough, yet firm, to sleep on later. I've had a pillow top that has lasted about 7 years but it has formed sagging where we lay and is also fast losing support where I sit even with rotation and flipping so it is time for a new one. I was thinking one of those "sleep number" ones and just make it really firm when sitting during the day and then changing it softer to sleep at night, but I don't know if people like them or not and how durable they are. Please recommend specific brands that you think would be the best for my situation.

Thanks for all the help in advice in advance!

Suzy