Mattress Forum

I'm considering a few options for getting a new mattress.  I've been researching latex mattresses, and they seem quite attractive, but I'm not sure I'm ready to invest that much money at this point.  Right now I'm considering this very simple setup from Foam By Mail:

3" Slow Recovery Foam
w/ 5" HD36-HQ (Medium) Foam
Twin Mattress (39" x 75")

http://www.foambymail.com/SRFTwin1.html

I'm considering 3" vs 4" top memory foam piece, and whether to go with the Medium 5" or a Firm 5" for the base, but my main question is:

Should I get a protective mattress cover, and, if so, from where?  I do tend to sleep hot at times (thus the attractiveness of latex), but if I had the right mattress (quilted? bamboo?) cover it should help with that, correct?

I'm a back sleeper, 5'7", and 150lbs.

Any thoughts, questions, suggestions?

Thanks,

BB