The dakine bags are awesome, I had one for a while but moved up to something a little bigger. When you're looking for a new bag you want to look for something that will fit a little more then what you currently have, so you don't need to buy a new bag if you buy a new lens or something. Also it's important to look for a bag that doesn't look like a camera bag, a bag that says canon or nikon really says steal me there's a camera inside. Try and find something that is weather resistant also.
if you want more of a shoulder bag, you should check out domke
I have a lowepro back pack, I got it because it holds my computer and a bunch of camera stuff, and doesn't really look like a camera bag