The Think's a great bag. Just to offer up the one that I use (which is really far more 'adventure' / wildlife / landscape specific).. the F-Stop Loka. Loka

I REALLY love this bag. It's more a frame pack than a camera bag in many ways. It's also VERY flexible, with multiple insert sizes. The only issue I've had is that F-Stop is rapidly growing, so delivery was a bit sluggish. The service, however, has been great.