[apexlocator]

F4 is really difficult to use indoors. You'd be using flash all of the time, adjusting FEC, bouncing, and having to do more in post IMO.

I would just take the 35L, but you'd have to be able to get into peoples' faces to get tight shots, which shouldnt be a problem if you are the official photog. Large group shots would be a little tough too.

To get more background/ambient, lower the shutter speed and open up that prime. Not familiar with the 6D other than I know its full frame, but you should also be separating focus and metering buttons if possible. That + lowering your FEC a bit is a good combo with the 35L.