At semi-formal functions, men can forgo a tie or bow tie, which isn't the case at a black-tie optional wedding. As for women, above-the-knee dresses replace long gowns at semi-formal events.

Brown/Agence France-Presse/Getty Images) After Oscars night, the beleaguered tie industry could sure use a new PR campaign. Many marquee men eschewed ... in a tie-less black dress shirt and ...