Mattress Forum

I am getting married in several months and my fiance and I are starting to mattress shop - well, I am.  He is in medical school in a state quite a bit aways from the state I'm in which I'm completing graduate school, so we can't test mattresses together very well.  He won't be moving up here until two weeks before the wedding.  My current mattress in staying at my parents' house (no dice on taking it), and his mattress is a really awful one that wouldn't be worth the cost of transporting to our new home.  Our budget is probably $600; we should be able to swing $700 max.

I am almost always a side sleeper who very occasionally starts out sleeping on her back...but I end up on my stomach often, usually after I'm supposed to be up and have nestled under the covers in an effort to sleep just a bit more.  I am 5'7" and 130 lbs.  I have had back problems - have a spinal fusion from scoliosis, so if something is too stiff and lacks lumbar support I can't be on my back for long without discomfort.  No real day-to-day issues, but I sometimes sleep in oddly and give myself neck problems.  My current mattress is a pillowtop with springs that I think is moderately firm.  I like the mattress, but I do use a thinner pillow - a memory foam one just about killed my neck.

My fiance likes to sleep on his back (and snore), but will also sleep on his side (...and snore) about 50% of the time.  He is 6'0" and around 185-90 lbs.  He thinks my mattress is too soft, but he has slept on really, really bad, cheap, ancient mattresses his entire life (I was in agony after sleeping at my future mother-in-law's house one night).  He does have some neck issues and uses an almost flat pillow.

I have been looking at memory foam mattresses and was all set to order one of these:

http://www.amazon.com/Foamex-10-Inch-Premium-Mattress-Natural/dp/B001E972O8/ref=wl_it_dp_o?ie=UTF8&coliid=I1RRTNV4PKME8Z&colid=WDDSHJ88QUQA

http://www.amazon.com/Memory-Foam-Mattress-Plush-Activated-Carbon/dp/B002AHX4PY/ref=wl_it_dp_o?ie=UTF8&coliid=I3VHL1IJ1NYTMV&colid=WDDSHJ88QUQA

http://www.samsclub.com/sams/shop/product.jsp?productId=prod1990006&navAction=

...but after stumbling onto this forum, I now I realize I have no idea what I'm doing.  I am trying to research, but it is overwhelming.  Suggestions, advice?