What's a good waterproof backpack for commuting?
I'm looking for a new multi-use bag for graduate school. I'd like a bag I can use during the week for biking to school (I have a 17 inch laptop), and on the weekends for long day hikes with my dog. It'd also be nice if it was waterproof, and it doesn't need to be specifically for holding laptops since I have a sleeve. Liz Harvey Denver, Colorado