I'm bringing my 5D classic, and definitely my 28/1.8 and 85/1.8 - my can't-live-without lenses. I will also have a S95 with me. Other things I could bring:
EF 20-35 (f/3.5-4.5 version)
430 EX II flash
I have the 85 f/1.8, but I would put it on the bottom of the list with the 50 f/1.4 if you wanted to go really light weight. Not that the 300mm f/4 is light either.
I think I would take the 20-35mm over the 28 f/1.8. Although the 20mm f/2.8, 24mm f/2.8 or some other wide angle lens would be my pick just for the focal length.