13 Black and White Semi Formal ideas dress, gowns, evening dresses White Tie: The most formal. Men wear tailcoats, white vests, and bow ties; women wear floor length evening gowns. Black Tie: Strict formal. Men wear tuxedos, and women wear floor length gowns. Black Tie Optional Formal: Tailored Fit Lt Blue Plaid French Cuff Non Iron Men's Dress Shirt Wilkes & Riley, LLC Black And White Semi Formal Attire For Ladies Black And White Lace Semi Formal Dress Tea TIL: In Western dress codes, technically a black tie event is still only ' semi formal', as fully formal dress is 'white tie', which for men requires a coat with tails. : r todayilearned 13 Black and White Semi Formal ideas dress, gowns, evening dresses