Back to the car camping that was briefly referenced... I have a plywood topped platform that I sleep on in my Cruiser, and the small self-inflating pad (Thermarest I think) isn't cutting it for me. I want something to keep me warmer, and something more comfy. Weight isn't a big concern, and the space it takes up is only of moderate concern. I usually just fold it in half with my sleeping bag in the middle and then run a strap over the whole thing while traveling.
Open cell? Memory foam? I'm not opposed to the simple 3" open cell pad from Smiths, but are there better options? Size requirement is roughly 30"x72"+. Keep in mind that I'm cheap.