The only thing I'd caution you about in using the timbuk2 or crumpler bags is making sure your camera has padding around it.

I almost always carry my camera in my lowepro bag - but after staying once in a questionable hotel, I put the bag out in my shed just in case anything hitchhiked home with me. And I'm usually super paranoid with my camera...

So when wanting to go on a quick hike, I stuck the dslr in a small messenger type bag inside a hat.

Then I set the bag on a table, walked away, and yep... the bag toppled off.

I now have a crack in my dslr body.