I have two suggestions. First, for the lens, I'd recommend the Canon EF-S 17-55mm f/2.8 IS USM. It covers a very useful focal length range (equivalent to 27-88mm on a full frame camera; for comparison, the EF 24-70mm f/2.8L is called the 'wedding brick' because it's a great focal length on FF for wedding, and it's heavy...). The fast f/2.8 aperture and IS will help you get shots you'd otherwise miss.


The second suggestion is more basic. Instead of dropping $1000 on the lens I just recommended, hire a professional photographer. You'll get to enjoy your daughter's wedding ceremony and reception, instead of fretting over taking pictures. For example, if you're the photographer, just who's going to shoot the pictures of you walking her down the aisle, or dancing with you at the reception? You'll also likely get better pictures (not trying to critique your skill, but you stated that you have little expertise). Also, if for some reason the pictures don't turn out well, if you didn't take them, the chanceswill be much greaterthat you'll get to see those grandchildren when they come along...