The 22 is the way to go. Holds a weeks worth of stuff and you never have to worry about a gate agent or FA giving you crap! Plus if I ever need more room I just pack some things in the clip on carry bag that they sell, but I hardly ever use it unless I'm going on vacation for over a week. You will learn when you start to pack a lot that you never use half the stuff you bring anyways. My suitcase for a 4 day consists of uniforms, tshirts and board shorts. Never have time to wear anything else.