For the 2+ months I was in SE Asia I lived out of my @metoliusclimbing Crag Station backpack. Just big enough for my rope, 14 draws, 4 slings, extra lockers, jug, GriGri, megajul, harness, shoes, chalk bag, shirts, shorts, pants, hoodie, rain jacket, boxers, socks, towel, camera, and sandals. Oh and toothbrush.
But when I ditched most of the extra stuff and went out for a day of climbing (like in this photo in Tonsai) the pack compressed down and carried nicely. And the shoulder straps and waistbelt stash away when you need to check the bag on the plane, and the burly fabric means no worries about it holding up to the rigors of travel.