I used to have a water bed. they suck, do not buy one. having sex on that thing sounds like Hurricane Katrina. and in the winter time it would get freezing.
now I have a squeeky, uncomfortable, POS.
I should just snooze on the floor with my sleeping bag. now that thing is great, super comfy and cozy. I got it off some junkie that wanted to camp with me once and then took off and left all his stuff.