I'm using a Lowepro Fastpack 350, which is a great camerabag and a nice laptop bag. There are three main compartments: The camera part for the camera and a few lenses / flashgun. Then the laptop part, which is also nice for some papers which shouldn't be folded.
Finally there's the upper part for whatever you want to carry around with you. A one litre Coca Cola bottle fits into that part of the bag: (What I had in my bag when I went to Hong Kong in February 2012: https://picasaweb.google.com/lh/photo/- ... directlink
- few changes: 18-55mm --> 24-105mm 4L | EOS 33v --> EOS 5D III | 50mm 1.8 broken)
Usually I have some accessories in there (card reader, flashgun, cable shutter realease, laptop accessories) but it's just nice for food or other things you need when taking a walk.
My girlfriend has the Fastpack 250, which is a bit smaller but hardly smaller from the outside; just the camera compartment seems to have shrinked so my 100-400mm wouldn't fit there anymore but just a flashgun.
Both of those backpacks have two straps, which is nice if you carry them for a longer time.
I like the versatility of this kind of bag and that's why I chose this when I went to China for a while. Also proved to be great in everyday life - with or without camera. I'd go for it again. OK, there are other nice bags - for example the Tamrac Evolution 6 looks pretty interesting but it has no compartment for a laptop or some A4 papers. It can hold a tripod though, which is not possible with the Lowepro.