Really, I should think that most any pack would workjust about everything out there can be expanded or cinched down, and its no big deal to find one that can fit one of the Eagle Creek organizers (great things; $22 for the 15" size).
But, certainly some packs are better than others. Patagonia makes a purpose-built commuting pack called the Vertical Mass ($125). It has lots of internal pockets and organizers such as a computer sleeve, a pouch for eyeglasses or small electronics, a water bottle pocket, and more. It has shoulder straps, of course, but it also has handles, so you can carry it like a briefcase.
Eagle Creek makes a commuting backpack as well: the Back Office (hahahaha! Who thinks up these whacky names?). Same drill: laptop sleeve, lots of internal organizers, and the nice touch of a back slip panel so you can slide it over the handles of wheeled luggage.
Lastly, while at the recent Outdoor Retailer show, I was smitten by the absurdly beautify yet utilitarian offerings of Fishpond, a company that caters mainly to the hook-and-line crowd. But they make an urban backpack called the Barcelona Street Backpack ($119). It has pockets everywhere for a notebook, clothes, and more. I like it in Moss Green.
Alas, none of these packs can be thought of as much more than water-resistant. But get a small pack cover (Sea to Summit pack cover, $32), and youll be fine.
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