This is a terrific web site and forum for those of us trying to educate ourselves. My wife and I want to buy a memory gel king. She sleeps on side and back and I sleep primarily on my side. I’ve rejected the name brands for all the reasons noted herein, but now am looking for factory direct outlets somewhere between Savannah and Charleston. Any help will be greatly appreciated. Also, can I use our existing king box springs covered with plywood as the foundation for this purchase? Thanks very much.
Hi gamafn,
I think post #2 here should help 
This would depend on what mattress you buy and what type of foundation is most suitable (see post #2 here). In general though I would tend towards a slatted foundation over a solid surface because it will provide better ventilation (see post #9 here). Plywood over an active boxspring (the kind with springs that flex) can also be unstable and I would treat this as a temporary solution at best and not a long term one. Most manufacturers will sell a suitable foundation with their mattress or recommend the type which works best but there are also alternatives for those who need or want them in post #1 here.
Phoenix