When I was potty training both my boys (at the same time, sleeping in the same bed) I used Protect-a-bed mattress protector. They are not sweaty or noisy. In fact I like them so much, I got one for every bed in the house. When the boys were peeing constantly all night, I put a saddle style mattress protector then a fitted sheet and another saddle style mattress protector and another fitted sheet. Each time they wet, I just peeled back a layer and rolled them over to the clean layer underneath and went back to bed. They absorb a lot and stay in place pretty well (not slippery on the back).
http://www.onestepahead.com/catalog/...tegoryId=86184
Another idea is to layer bamboo velour with a "batting" of a product called ZORB with PUL for the waterproof lining and make your own matress pads or adult sized diapers. Usually used to make cloth diapers or mama cloths. Super absorbant, soft on the skin, but still creates laundry.