I have just picked up a Lowepro AW650 that holds everything (and it feels like that includes the kitchen sink!).
EF gear is my system of choice - I shoot film for myself and d**** for business, although I have recently had inquiries from clients asking for b&w imagery for their projects as well; surprisingly not only in 35mm but also MF.

I try hard to have some down time on shoots to shoot for myself, so that means I pack my trusty EOS-1 on every shoot. Adds to the weight, but with my assistant carrying most of the gear, I just put this baby into a smaller bag with my folder as well - gives me the option of 35mm & 6x9 in both B&W and colour too.

So, the following gets taken on board every flight, split between two bags:

Lowepro MiniTrekker:
EOS-1
28mm f2.5
Folding 6x9 Kodak Junior
Film: 35mm & 620

Lowepro AW650:
Macbook Pro 13"
5D MKII
17mm f3.5
28-70 f2.8
90mm TS f2.8
180mm f2.8
300 f4
550EX
Pocket Wizards x3
Filters & other digital requirements

For my MF kit, it's a GS-1 with the following:

Body w/ AE prism
65mm
110mm
Various filters, cable release etc

Still looking for an elusive 250mm - once I have that I'll be happy with my MF kit.
Rarely used on shoots these days, so it only comes out to play when I want to shoot for myself, which, although not often, is an absolute joy to use.