My daughter and I like the british designed CabinMax style carry ons that are a backpack. They are exactly the size Norwegian/Norse, Ryanair, Easyjet, etc. which means pretty much all the budget airlines. They're about 40-42 liters, firmish canvas rectangles with zippered compartments, and they hold a LOT. 8-10 outfits. We have used them on month long trips and only did laundry once and on several 16-18 day trips. Amazon and some of the other brands have copied them so there are plenty to choose from now.