The few weddings I've shot, I wear slacks, nice shoes and a shirt with tie. Last wedding I shot for the neighbor kid, who grew up with my kids. The food was pizza and beer, so you can imagine just how the guest were dressed. Infant, the only the folks that were properly dressed were the parents, and wedding party, it looked as through they were dressed to party.
All-in-all, it was fun. Unfortunately, the marriage lasted all about six months. So far of the three weddings I've shot, only one couple still remained married. So, I don't shoot too many wedding