Another consideration is the HMG Daybreak pack — pricey at $229 but appears to be durable, well-constructed, and functional. Only listed as 17 liters (main compartment only I believe), but it swallows a lot of gear. Just don’t max it out completely at the top and it will stow under the seat. I flew with mine and really liked how it performed on the trail — simple zippered access to the main compartment and the usual pockets for drop-in convenience. Small zippered pouch on the inside for keys and the hip belt is slightly better than the pathetic wings many packs have. Easily tucks away for airplane time.
