Ask people who travel for a living to talk about bags and you will swear they’re talking about partners. And a bag is a partner, a vessel you trust with your most private things. Its flaws become painfully apparent as they nag at a spot just beyond your clavicle. Yet it stays at your side as you walk forth through the world. I am married happily to my wife, but a foolish libertine with my bags. I have owned at least 11 different ways of carrying a laptop. In a fit last year, I ordered four new bags and returned all but one. Now it, too, feels overly bulky, its opening too small. It sits unloved in a corner of our guest room.