I'd recommend you start the legwork by spending some time at Western Mountaineering's website. Also check out Montbell's website. My local outfitter told me that Golite is coming out with some pretty good looking bags - don't know if they're on the website yet, though.

After you do a little research, you'll be able to give everyone a better idea of what you're looking for - and then you'll get so many specific recommendations you won't have any idea which one to choose!