Slacks or a skirt or a dress with a sweater or a jacket is appropriate for women. Men can either wear a suit or a sweater or a blazer. You will meet their mentor and his wife and possibly his family if you go over to their house afterwards. Be comfortable but dressed appropriately. The banquet is full dress for the cadets and the same for guests.
Some people wear formals and tuxes.
Others wear dressy knee length dresses or a dressy pant suit and the men wear suits. But it is a dress-up occasion. Female dates generally wear either a cocktail dress or a long formal and the male dates wear suits or tuxes. The cadets wear full dress or the females can wear the evening dress option. It is the highlight of the weekend.