All interesting and thanks for everyone's thoughts. Today I am leaning towards the 24-105 + 17-40 + "Shorty 40" (for low light situations) in my Retrospective bag. I love my 70-200 but on past trips, based on EXIF on LR, rarely used it (this is my first trip with the 5D - my old kit was a crop with 15-85 + 10-22 + 70-200). I did use the WA zoom for interiors. I know that I'll miss whatever I leave home, but I've lugged a heavier kit in temps over 100F and it is no fun.
Since you're trying to keep weight down, it seems a bit odd to me to take two overlapping f/4 zooms. How often did you use the 17-40 wider than 24? If seldom, leave it behind. If you hardly ever use the 70-200 because you hardly ever go beyond 70mm (as opposed to because you seldom go beyond 105mm), what about taking 17-40 + 50mm prime?
The advantage of the 17-40 is that it is weather sealed and does wide as wel as 'normal', a real asset if changing lenses is a no-no (ie dusty or wet environment). This is why I carry both the 17-40 and 24-105. Depending on the conditions I often pick a lens and stick with it during the rest of the day.
