I like the Thermarest Neoairs, on top of a ridge rest. The Neoairs pack down really small, on the order of a 1-liter Nalgene bottle. The ridgerest doesn't but it can ride outside the pack, on the side or underneath. Underneath is good in that it protects the bottom of your pack when you sit down.
That's exactly what I use as well. I pack the Neoair in the pack, and the Thermarest wraps around my tent and goes under my pack lid--never damaged one. I am 49 years old and have backpacked countless times, using only a Thermarest (or, further back, a different foam pad). But a couple of years ago, I started carrying a Neoair as well. I will never go back. I now often can sleep all night without waking up. Before, on just the foam pad, I was constantly turning over and having to squirm around in my mummy bag to get comfortable. I do have to carry another 16-ozs of weight, which I was reluctant to do, but now I am much more rested, alert, and happy during the day (especially important on hunts). As I get older, I always am looking for ways to shave weight, but I will never go backpacking or backpack hunting again without a lightweight air mattress.
