I also start out with my pad fully inflated (usually because it's been in a chair kit, and firmer is better), and then let air out as Phat and others describe.

I went the Neoair route - and then retreated. I'm now back to a 48" Prolite Plus,simply because it's more convenient to use; it doesn't have to be blown up, and it let's me store my pack under my feet. The Neoair was comfortable, but I found the only one I liked was the all-season, which was 60" long. That forced me to store my pack less conveniently. Since the all season weighed the same as the Prolite Plus, I decided to stay with the Prolite Plus, and have not regretted my choice even once.