I'm a fan of the Patagonia MLC, <a href="http://www.patagonia.com/us/product/mlc-bag-maximum-legal-carry-on-bag">Patagonia MLC</a>, which I think I first saw recommended on Cool Tools. That said: I pack light -- that back goes with me for a long weekend or a two week trip -- and the laptop is light too. I have an 11" MacBook Air that I have a minimal neoprene sleeve for. That, the charger, various cables and accessories for my phone and camera all fit in the slimmer of the two main compartments on the bag.
<a href="http://www.patagonia.com/us/product/mlc-bag-maximum-legal-carry-on-bag">http://www.patagonia.com/us/product/mlc-bag-maximum-legal-carry-on-bag</a>