lens' for weddings vary, i hear of people shooting a wedding with just a 50mm or with a 28-125mm or with 75-300mm etc... even 28mm L series
as a wise man once told me,
"It isn't the lens that matters, once you learn to use all your lens' to their maximum potential you can use any lens for almost any purpose."
got that from a "what lens to use for weddings" topic on a nother forum i used to be part of not long ago, it was such a great little forum
but the guy who told me the above quote said that he just grabs a random few lens' when he goes to shoot a wedding, there is no set lens that he uses for it, and his results are 99% of the time, stunning