Black tie means floor length, and this is where the floor-length dresses live: satin cowl necks and pleated one-shoulders, velvet bodices, lace, organza, and metallic for galas, formal weddings, and the holiday party that asked you to dress up. Mini and midi stay on the cocktail page; everything here reads formal from across the room.
For a black tie wedding guest dress, the deep colors are the safe bet: burgundy, emerald, navy, plum, and black. Add strappy heels, a clutch, and one real piece of jewelry. See also cocktail dresses, wedding guest dresses, holiday dresses, and satin dresses.