I have a very lightweight bag from Swiss (like the army knives) which takes pretty much everything I'll need for a week. Mind you, I don't pack a ton of stuff so I can easily fit 6-7 outfits in there and it will fit under my seat. My preference is to check it but I do carry it on when necessary or if the load is light. I also take a backpack from Eddie Bauer for things I need on board which includes food, entertainment, small toiletries and a change of underthings/socks along with my blanket since I'm always cold. You name it, it's probably in there. That backpack has lasted through many trips with no damage. I would buy it again in a heartbeat and Eddie Bauer will replace it if it ever does have issues since it has a lifetime warranty.