It's the reason I specied Thermarest with chair addon. You'll be taking a mat/airbed of somesort so make it a Thermarest because they're simply the best for comfort, ease of use and packing size. If you've got a Thermarest, you've also got a chair; the clever chairification component has no more weight/volume than, say, a belt.
Th only downside to Thermarest is cost. Oh, and if you're climbing and one starts to blow off the crag, don't stamp on it if wearing crampons.