I would have said Crumpler Muffin Top 7500 a couple of weeks ago. I have one, it is a great bag, very discrete (if this is important to you). However, it is just a little bit small, Crumpler themselves are very optimistic about what you can get in there. Their bigger messenger style bags have inserts which means the internal volume isn't much bigger.
The 70-200 and 24-70 are brutish lenses and I really don't think you are going to get them in there.
For reference, I have a 5Dmk2 with grip and and 24-105 f/4 L. I could just get this in the MT 7500 with room to spare for the 17-40 f4 L and a 580EX2. Even then I wasn't entirely happy as lens down, with the 24-105 mounted, the cam was a little top heavy and tall for the bag. For my last cam, a 40D (17-55 and 10-22) it was just about right.
A couple of weeks ago, another thread on this forum alerted me to the Domke F2. The OP was himself changing from the MT 7500 so it was a very useful post. I tried (and failed) to snag one on e-bay and ended up getting one from WE instead for ~£130.
The Domke F2 is that little bit taller, little bit longer and little bit wider than the Crumpler to make it spot on for me at least. It will comfortable take a the 5Dmk2 and grip with 24-105 mounted (hood reversed), 17-40 (with hood in a side pocket), 580EX2. There is also one compartment free which will be fine for a 70-200 when funds permit although I couldn't say that a f/2.8 would fit with the hood reversed.
It wasn't cheap, but is well built and again discrete. The shoulder strap is long enough for either shoulder or messenger style wearing.
