Banquets are very common for corporate events, since businesses often hold them for staff or clients. Therefore, those who are a part of a large organization will often attend a banquet or two. Other men only find themselves there, when they attend weddings of friends and family members. The expected attire can vary, depending on the formality of the event.
Single-breasted jackets need a black cummerbund and black tie. The cummerbund is a broad waist sash. The double jacket does not need a cummerbund. Besides a black tie, you can wear a tie and cummerbund with patterns.
When the banquet requests cocktail attire, men should wear their best suits, but not a tuxedo. Some weddings are black tie optional. This allows men to wear a dark suit, preferably a black, grey. When the invitations mention black tie, men are supposed to wear a tuxedo. White dinner jackets are an alternative to the black tuxedo for a tropical banquet. The white shirt and tuxedo should never be pure white, but should instead be a creamy shade. Black trousers can go with the white dinner jacket, or you could wear matching white trousers.
Fashion for the wedding banquet is not as stressful, since most people will focus on what the bride and groom are wearing, instead of what the guests are wearing. However, not dressing formally enough can be disrespectful to the bride and groom. Morning and afternoon wedding banquets usually ask for lighter and more casual wear than evening weddings; often a sports coat, slacks and a tie. Suits are even better. For evening weddings, men should wear darker, more sophisticated fabrics for their suits -- to suggest formality. At weddings, colors should be conservative, since very attractive colors draw attention away from the bride and groom.
When the banquet stresses casual wear, men should still wear slacks, a dress shirt and dress shoes. When in doubt, men should dress as well as possible. Where the banquet is being held influences the appropriate dress. The more informal the banquet hall, the less formally you should dress.
At retirement banquets, people should dress nicely in the evening, but wear more casual attire at lunch. People should dress nicely at anniversary and birthday banquets. At awards banquets, guests can wear what they normally wear when they go to work.