Think Tank International v 2.0 camera bag ($370).
This bag is spacious and well-built. It's the perfect size bag for world travel due to its internationally-approved cabin dimensions. It's got some weird lockable items, so you can lock your bag to a table and walk away (don't know why you would, but it's there for you). The aluminum carry handle is a bit flimsy, but so far, no problems with it. Absolutely love the sewn carry handles.
5DMKIII, 5DMKII, 70-200mm, 24-70mm, 50mm, 2x Extender, Marshall monitor, Zoom H4N, Zoom H1, JuciedLink pre-amp, Rode NTG-2 mic, Manfrotto magic arm, adjustable arm, Nasty Clamp, Litepanels Croma light, headphones, (not shown: XLR cable, intervalometer, boom pole, tripod). Basically: 2 DSLR cameras, 4 lenses, monitor w/arm, audio package.
< The secret is in the wheels. Very similar to inline skate wheels, these roundies deliver a sturdy roll.
< One of the best attributes of the Think Tank Intl 2.0 is the ability to hold a 17" laptop in a stretchy front pouch. I put the laptop in a neoprene sleeve, and it slides out perfectly at airport security, or on the plane.
OVERALL: A+ / I'm always looking for the perfect bag, and this one may be close. The jump over from shoulder carry to wheels has truly changed my life. You'd think it would be a no brainer, but I was stubborn. If you're considering moving to wheels, I highly recommend starting with the Think Tank Intl 2.0 camera bag.