In addition to all the good suggestions above, take a look at Kata (www.kata-bags.com/). They make a bunch of great bags that meet most needs (I have two I love) and they also have a pretty good bag chooser.
I have the R-106 (big) and the 3N1-20 (smaller). But, that's just two of a ton of choices. Enjoy.
I have the UD 40 and can fit the 5D2 with 70-200 f4 and 2 other lenses, plus room for CF cards, flash, etc. I can even fit a netbook in the interior pocket, and it's not very bulky at all.
5D2 with one of my lenses attached
mini USB cable
extra CF card
That all fits in there fine. So it can definitely hold a lot.
They have a couple versions that are bigger and could fit more lenses. I keep my camera with an 18-55, 55-200, extra battery and charger, extra SD cards, my iPod, and lens hoods in the bag. For you I might suggest one size bigger.
These would probably suit you a little better: tamrac.com/frame_ultrapros.htm
It's easy to get into the camera (center slot) and 2 lenses worth of storage by just swinging it around with out taking it off.
You can also add on extra pouches (point and shoot size or bigger) and a 32 oz. water bottle mesh pouch for hiking.
The next size up is about as large as a full backpack so unless you want even more space, the 200 is great!
The camera with 24-105 will fit fine, but not with the hood reversed. I put the hood in the front pocket, with the case for my 500D close-up lens inside the hood (you could also put filters in there). Then in the main compartment there's room for my 24-70 (you could easily get a 50mm in there instead), and in the top pocket goes my 430EX flash and the battery charger.
Finally I can get a leg of the Gorillapod through one of the funny little loops on the side.
Hope that helps
I love this bag, it really works well for me, but the one thing it won't accommodate is longer telephoto lenses. It won't, for instance, allow me to pack my 70-200 f4. If i need that, I use a LowePro Mini Trekker AW instead.