At the Apple Store four employees recommended the Brenthaven and said that they did not have them in stock. Three others recommended the Timbuk2 Commute for the 15" PB and also the 17" PB. What sealed the deal is that the people using the Brenthaven said that they fit the PB and a couple of things, but not a binder, PB, and a textbook. I had them demo it for me and honestly I have to disagree, I think a textbook can fit in there, but the Timbuk2 was nice looking. It is fun looking and I just kind of think it's the better fit for me.
HOWEVER, BE AWARE. The Timbuk2 is $100 and DOES NOT come with a padded strap. For me this is 100% unacceptable. I had to order one for $10 and $6 shipping. It was quite annoying, but I love the bag. In the meantime I'm using an older strap until this one comes in. Also, if you care, the back of the laptop bag is super sweet!
Good luck.