Weiden+Kennedy are one of the coolest ad agencies I can think of. I went to Semi-Permanent in Sydney a few years ago and heard 2 art directors from W+K Portland speak - their approach to coming up with ideas is so different from what is taught in a book!
Having said that, I found these lessons from John C Jay, Executive Creative Director of W+K (pictured above), very interesting. Although some seem like common sense, it's nice to have a reminder from time to time.
My favourite is: "Travel as much as you can. It is a humbling and inspiring experience to learn just how much you don’t know."
Read them here.