Hi Twokids,
I think the most effective method of buying a mattress is to test each one against your “ideal” PPP (Pressure relief, Posture and alignment, and Personal preferences). Using another mattress as a “target” rather than your own personal needs and preferences can lead to some very confusing testing and limits your selection to a mattress that may not even be the best for your needs and preferences. The “feel” of a mattresses is very subjective and our memory of a subjective feel or even the specifics of how a mattress performs doesn’t last more than about an hour or so or at best a day. So I would test each mattress individually and “measure” or test each against it’s ability to relieve pressure, keep you in alignment, and for the various preferences that are important to you. There is more about “mattress matching” in post #2 here and a list of the various preferences that may be important in post #46 here that should help keep your mattress testing as “objective” as possible.
There are some guidelines on the site for weight and height here, for sleeping positions here, and about how these guidelines can be affected by different types of layering but these are only generic (and the whole subject of designing a mattress by specs can be very complex) and apply to “averages” not to any particular individual. Because there are so many variables involved in both mattress layering and individual differences in body types (even with similar height and weight), sleeping styles, and sensitivity to different elements of how a mattress feels and performs, I would put much more emphasis on your own testing than on the guidelines which are good as a starting point but not necessarily an “ending point”. You have some good factory direct outlets with some knowledgeable people in your area and their help and guidance can also be invaluable. Local manufacturers may be more knowledgeable than some of the regional manufacturers which have many outlets and may not always have staff with the same degree of knowledge at every outlet.
Electric blankets are not a good combination with memory foam which is a temperature sensitive material and it will soften the memory foam more than it’s design and can also shorten it’s life. While most manufacturers recommend against it and you would probably be risking any warranty coverage … if you absolutely have to I would use the electric blanket for only a short period of time (say 15 or 20 minutes) preferably before you go to bed and on less than maximum heat and then turn it off for the night. Memory foam is designed to respond to body heat and it will become much softer and not perform the way it is designed to with an external heating source.
Sonic has done lots of testing in the area so his suggestions are from experience 
… and in case you haven’t seen it … the Orlando list of manufacturers in in post #2 here. You have some very good quality and value choices near you.
Phoenix