A full length gown is definitely appropriate for a very formal, evening wedding. Weddings are special events that call for dressing up. In today’s world there are no hard and fast rules when it comes to fashion. However for formal events a long gown or a dressy cocktail dress is appropriate. Since you describe this as a very formal wedding at 5 PM a long dress is definitely the way to go. Any color dress will be alright except white which is reserved for the bride.
What Should the Wedding Guest Wear?
Be a stylish wedding guest! Weddings are to celebrate, occasions to dress up. The wedding invitation provides the information to help you decide what to wear. Daytime (morning and afternoon) weddings are more casual than evening or formal weddings. Today any color is appropriate with the exception of white which is reserved for the bride.
Party pockets? Would you wear an evening gown with pockets? Forever pockets have been popular on dresses, skirts and pants. Now young and seasoned designers are adding pockets to the cocktail dress and evening gowns for a casual chic look. These designers feel that pockets can give a four figure priced dress a less pretentious, relaxed elegance.