Depends on the type of wedding. Plenty of red, green or black dresses from midi-maxi, couple of patterned midis, couple of dark blue, one black + a print, one white with black floral, a favourite right now for when being covered is more appropriate is a longsleeved black broderie midi.
However, I'm pretty sure every single one will fall foul of some wedding guest rule or another, as the rules change depending upon who is posting.