Another sleeping pad Vin and Gwen considered is the Therm-a-Rest Z-rest. Like the Ridge Rest, The Z-Rest is a light sleeping pad made of closed cell foam. Unlike the original Therm-a-rest, these pads do not air up. This makes them less cushy, but you don't have to worry about getting a hole (or 2...or 3...) in the pad while you're out hiking.
The full length pad measures 20x72x3/4" and weighs 15 oz. We originally wanted the Z-Rest because it folds up, which makes it easy to pack, but it is twice the cost of the Ridge Rest normally, plus we found the Ridge Rest on sale. We have laid on both the Z-Rest and the Ridge Rest in the store, and find it hard to distinguish between them--they feel like that have about equal comfort levels to us. (we laid the Ridge Rest and Z-Rest side by side so we could have half our body on the Ridge Rest and half on the Z-Rest).
A note to shorter people out there---Therm-a-Rest also makes a Z-Rest dog pad. This is really just half a full length Z-Rest (meaning, it's 3 feet long). If you are about 5'4" or so, this would suffice as a 3/4 length pad. Better yet, if you are friends with another short person, buy one regular length Z-Rest and cut it in half.