I find black patent leather slip-ons to be perfect for the smart but informal occasion. As a case in point, I wore my (D&G, very plain) pair to dine with friends in their home on New Year's Eve. Otherwise I wore a dull gold silk shirt, untucked, over a black silk long-sleeved tee shirt and flat-front black wool crepe trousers. Calf shoes (even my dancing pumps with the grosgrain bows) wouldn't have been right with the gold silk, I don't believe, and while my black velvet pumps might have worked visually, they are so analogous to slippers that I make a rule only to wear them in my own home. As some of the other men were in jackets, none in ties, between the shirt and the shoes I felt appropriate to the occasion while being neither overdressed nor underdressed. And that's not a bad way to end, or begin, a year.