One of my favorite computer bag companies is Waterfield Designs of San Francisco. Its bags are not only stylish, often mixing leather, waxed canvas and ballistic nylon in ways that please the eye, but they also just plain last. A case in point is the Waterfield Travel Express bag I purchased years ago for a MacBook Air, which is still going strong as an iPad bag (it can carry two easily) and still looks like it did when I unboxed it for the first time. Well, Waterfield has introduced an amazing backpack -- the Staad BackPack (US$319-$329) -- that carries on the tradition of design and function that the company is known for. Read on for a review and a chance