Upload & Sell: Off
Great suggestions above, either lens plus a fast prime or two would be my choice.
My target three lens kit is the 17-40L, 24-70 f4L IS and 70-200 f4L IS (I can't afford the f2.8 glass just yet). But given my budget I'm more likely to get the 24-105 f4L IS, I've seen the images that it can produce and they are stellar. I'll probably get the 6D kit with the 24-105 just for the extra 35mm in reach, and be quite happy.
What I've been using is film and crop digital bodies. On my crop bodies I usually carry the 10-22, 50 f1.4, 70-200L (and 100L IS macro). On FF (only film so far) bodies I use the 17-40L for ultra wide, but if I had the money I'd get the 16-35L II hands down.
Regarding the 16-35, as Michelle mentioned above, ultra wide lens require a bit of practice, below 24mm distortion can get pretty funky, but it's also quite usable; even correctable in post...
No mater which lens you choose I'd pick up a faster prime like the 28 f1.8, 50 f1.4 or 85 f1.8...any of these three can really help in lower light situations, are lighter and less noticed...even the 35 f2 is a nice little lens!
Best wishes on your trip, enjoy family n friends and the wedding; they are quite the event