I carry a 5D, 24-105, 35/1.4, 15mm fisheye, 580ex, and a 70-200/2.8L IS II with 2x TC III all in a ThinkTank ChangeUp.
I carry a lowepro 650 All weather bag. It could carry 6 of these lenses, and a laptop. And then you'd never lift it off the ground. It is a great bag, but can easily be packed to be too heavy. I have a wheeled art case that holds it and will often use that when I am "packing heavy"
I carried everything I said all day every day all around Orlando for 12 days straight. And I'm a little guy.