The ThinkTank Airport Security^TM V2.0 or the slightly smaller Airport International^TM V2.0 rolling bags both make fabulous roll-aboard carry-ons.  If your preference is for a large backpack that can serve as your carry-on, they offer several great models.  To check out or purchase ThinkTank products, click here:  http://www.thinktankphoto.com/affiliates.aspx?code=AP-246.  When you order merchandise totaling $50 or more you will receive a free Think Tank bag.  You can check out the choices here: https://secure-services.net/thinktankphoto/purchase/choose_gift.html