I would avoid tan shoes with a dark suit. Dark brown or black shoes are a much better choice. In theory you should avoid wearing pinstripes, which give off an office look, to a social event, but I don't think 98% of people outside of SF care about this.
Dark suit is not very descriptive. If could be either a dark grey or dark blue or, heaven forbid, black. It's also not clear how formal this event is. Is it black tie optional or is this something that you will see some people wearing an odd jacket and tie instead of a suit? A white shirt is the safest bet for a truly formal event with a tie in either a shade of blue or grey (blue with a grey suit, grey with a blue suit). If the event is less formal, you can get away with something with a bit more color (light blue, pink, lilac, though you can probably get away with light blue even at a more formal event and nobody will care). Pretty much any color other than black or light blue ties work on a light blue shirt (be careful though re: having too much blue if your suit is navy). Pink can handle blue and burgundy ties well. Lilac can handle dark blue and green ties pretty well.