Marla the recommendation for formal attire is tux or Dark Suit; i.e. Dark Grey, Navy, Brown even light color suits will pass. A nice tweed sport coat would fall under Informal or Smart Casual for a guy. Also, it does depend on what you plan to wear. If you have a formal full length gown/dress, he may definetly feel too casual. Why not try to work with your outfit first, renting a tux is a reasonable and very convenient way for him to travel. The ship rents tuxes with orders placed in advance and he won't even have to pack or carry it. This could include the shiney black shoes, too. Lot's of guys rent and also look great for those formal pictures which you can bring home to show friends and family.