Different types of weddings call for different versions of formal wear. These general guidelines match looks to mood.
For semi-formal daytime weddings, the male party should skip tail coats and opt for suits (navy or charcoal are great year-round, khaki or whites for warm seasons) and white shirts.
For semi-formal events in the evening, black tie is increasingly popular. Go with a dark tuxedo and bow tie worn with a cummerbund or waistcoat. Again, white shirts, with wing or turned-down collar.
Formal daytime weddings offer choice of tuxedos, kilts, or morning suits. Match with a white shirt, waistcoat to match jacket, cravat or regular tie, and top pocket hanky if desired.
Formal evening events are nearly always black tie or kilt equivalent. Chose a classic black tuxedo with a white wing or spread-collar shirt, black bow tie, and matching waistcoat or cummerbund. Formal ties are a more contemporary option.
For summer weddings or tropical locales, white dinner jackets can look very classy.