I have a LowePro Fastpack and it is just about perfect for travelling. It's split up in two halves - up top is a compartment for anything you fancy and down below is a nice spot to store your gear. There is a lot that can be stored there - I typically have two bodies and lenses on me, but there is room for one body with a mounted lens, three additional slots for lenses (or 1 body and 2 lenses) and two speedlites. There is another compartment for a laptop.
Best of all, it doesn't look like a camera backpack and there is a flap that hides the zipper away from prying hands. The flap itself is secured by two latches so anyone trying to get into your backpack would have to unlatch them, lift up the flap and then unzip. You'll notice!
Fully loaded it does weight a tonne, but it distribute that weight really well across the shoulder straps and a strap across the stomach. For normal use, with your listed gear on board - I wouldn't have any troubles carrying it around for a day. I used to have a 60d and 15-85 combo with two additional lenses, I suppose thats comparable to the weight you carry around.
I have yet to be refused access anywhere because of my backpack. If a shoulder bag is more your style then go for that , but then you have only one shoulder to carry that weight.