I agree that the 16-35mm f/2.8 II is a great option. At first the wide end of it is too tempting, and the shots one tends to take are not as good as someone with more maturity using a super wide angle 16mm focal length (just speaking from my own mistakes). Now I tend not to use the 16mm end of it as much, but for close spaces and uses for which wide angle is appropriate, it's a life-saver. An important group of people might happen to line up where there is no space and then 16mm is needed. But I prefer the range from 24-35mm.
For that matter I have been finding tremendous success with the 24mm f/1.4L II. I believe that using prime lenses helps me correlate the photo's perspective better with the human experience at the event. Humans don't have zoom lenses for their eyes; rather, they make small adjustments in position or distance to perceive things. A prime lens leads the photographer's style to make the same adjustments unconsciously, while a zoom lens does not.
So if I have the ability to set up the shots, like the pre-wedding photos, then I like the 24mm f/1.4L II, and I am beginning to be completely comfortable leaving it on for the entire wedding.
Note that I would never risk taking a critical shot at f/1.4 as mentioned earlier in this thread, unless I had time to carefully use contrast detection autofocus. At f/1.4 and as soon as a picture is cropped or enlarged, it does matter exactly whose face is being focused on, and it's hard to tell which face the camera chose at the instant the picture is snapped.