They have a couple of other really big backpacks that might work as well.
Heh, now that I look at the picture again - are those the exact same two lenses you mentioned? :-) Could be.
Cheers
James
Check out the Tamrac Super Pro line. I have the 613 and use it to carry all my lenses and bodies. As for depth, you can definitely put 2 1Ds's in there with a lens attached to each. I don't think that you could mount the 100-400 and the 24-70 at the same time though. In fact, I don't think you could mount the 100-400 and have another lens on the other body. Worth trying out though.
Here's a picture of their largest bag.
BTW, the 613 is just barely carryon sized, and can be a tight fit height-wise in some overhead bins. It does have space for a laptop in the back pocket though, which is nice.
Just go for a bag that holds the bodies and lenses and little else - From experience, I can tell you it will save your back braking!
I use the Tamrac Super Pro 19 http://www.tamrac.com/619.htm it is exactly Carry on size when you take the laptop out of the laptop compartment (it is big it can hold my Dell Latitude with UWXGA Display) When I do Air traveling I put my laptop in it in a light textile bag (the ones you can buy instead of a plastic or paperbag in supermarkets here in Europe) and take it out when I board the plane. with the laptop in it it wont fit in all overhead compartments.
You can definitely overload these bags. They're not bad when you've got other luggage with an extendable handle as you can slip it over the handle and piggyback it. I originally got it as a place to store all my camera gear in my office, but decided to try it out on a trip. I used it as my only carryon, and although it was heavy, it was pretty decent. The backpacks with wheels are very nice, I just wanted something that I could easily shoot from if the need arose, and these met that criteria.
Yeah, the rolling backpacks don't meet the "ready to shoot" criteria very well. It wouldn't be easy to just "whip out" that camera w/ the 100-400 lens on it...:-)
Cheers
James
Of course after carrying one of the shoulder bags around, I'm not sure my back meets the 'ready to shoot' criteria either!