I'm getting a Toploader 75 pro AW and tossing that in an old eastpak backpack i have.
It holds a 70-200mm lens so you should have a look at it.
Pros of my system:
-Doesn't scream CAMERA BAG.
-Added protection of the eastpak's Cordura fabric. (very durable to abrasion they say).
-Can put it in any other backpack I want.
-Can buy additional lens cases that clip on.
Cons of my system:
-Can only carry 2 lenses and a flash. 1 lens if it's a long one.
-Bag in a bag. Need to zip the backpack to get to the toploader and unzip that to get to the camera.
PS: Now i need a camera to actually put into the bag. The only reason I bought the bag before the camera is because my amazon gift card was going to expire.
I would of gotten it anyways. It's an awesome bag