Attire
Tux vs Suit
A tuxedo features satin lapels, satin side stripes on the pants, and is reserved for formal evening weddings; a suit is appropriate for daytime, semi-formal, and most modern weddings.
A tuxedo is identifiable by satin (or grosgrain) details: a satin-faced lapel, satin buttons, and a satin side stripe on the pants. Tuxedos belong at black-tie weddings, typically evening ceremonies starting after 5pm.
A suit is the default for daytime, semi-formal, and most modern weddings. Color trends: midnight blue, charcoal, and tan dominate modern weddings; classic black is still the safest evening choice. Most groomsmen prefer suits because they can re-wear them; tuxedos sit in the closet.