Best for longer adventures: Timbuk2 Aviator wheeled backpack

The 66-liter Aviator is the one big bag every long-hauler should own. Roll it duffel-style on skateboard wheels, check it, and hit the lounge. Upon arrival, bust out the backpack straps and hip belt for an easy hike to your hotel. There's also an integrated rain fly, compression straps, and plenty of handles. [$260;]