... like the pacific northwest, you might want to look into ortlieb panniers. they make several totally waterproof styles; i use the mini-biker and have been happy with them from day one. they're really well made and last forever. (it's rare when i can get something for the bike that *never* breaks, or needs attention, and always works as promised... so i get a little excited about my panniers!)

the only downside to most of the ortlieb panniers is that there are no inner compartments for organizing your stuff. but then again there are no little zippers to break and waterproofing is not compromised.

http://www.ortlieb.com/espal_hau_p.htm

-junebride