Mattress Forum

I am hoping someone can give me guidance about buying a new mattress.  First let me say that I just discovered this forum and am so glad to have found a resource for mattress information.  I would rather buy a used car at this point :)  I am on my 3rd replacement Kingsdown mattress. The first two were body systems in green and had latex toppers. After 6 months or so they developed massive ditches and were labeled defective by Kingsdown. They just sent me my third one, which is a series 800 and it is so firm that I am waking up with my shoulder and arm numb.  I've had it for three days and have yet to have a good night's sleep. The place I bought it at (not Sleepy's) does not carry any other brand, so I either get another Kingsdown or bite the bullet and buy a whole new mattress.  I'm at the point of buying the new mattress.

I am a fairly small woman--5'3 and about 130, yet I have pressure points on my shoulders (side sleeper) and lower back pain if not supported. I like a more cushioned top, but know the dangers of pillowtops and impressions.  Does anyone have suggestions as to the best manufacturers right now, where I will not have to replace the mattress in 6 months?! I have many brands available to me as I live in New Jersey and there are a lot of places to go to.  I am thinking of a Shifman since you can turn them, Sterns and Foster or a latex bed of some kind.  Thoughts? I would appreciate any feedback and so would my aching shoulders and back.

Thanks

Amy