[ducktapeguy]

x3 on using a duffle when travelling. No matter how expensive a bag you get, if there is stuffed strapped to the outside or loose hanging straps, they'll get chewed up, torn off, or just cut up in the conveyers. Also, it'll prevent the bag from getting a hole worn through where the internal frame presses against the material.

A duffle also gives the baggage handlers something easy to grab, rather than a tangled mass of compression straps, daisy chains, and shoulder straps on a backpack. These just weren't meant to be used to throw the bag around. I use a large nylon duffle, it's cheap, water resistant, and light weight. If you're going camping, you can wrap your sleeping pad around the bag before putting in the duffle for more protection.