Sam would point out that "formal" attire in Hawai'i is simply wearing your "nice" aloha shirt with a kukui nut lei, and he wouldn't rat you out if you wore that. At cowboy weddings, formal attire is "nice" jeans, a button-down shirt, and a cowboy hat and boots.

But this is a castle. If the bride catches you wearing something like that, you will be cast into the outer darkness where there is weeping and gnashing of teeth.

So, dress as a civilized man or woman attending a castle wedding for a lord and lady. Suits and floor-length dresses & gowns are advised. Color is also encouraged, because the only thing we would be mourning is your lack of it.