You are correct about the tux issue. On my cruise this past July, there were only about 4 or 5 men who didn't wear a tux on formal nights. For informal, most men wore suits and ties, or a sports coat and tie. The only night they didn't wear jackets and ties were on the casual nights. Crystal is a very dressy ship where just about everyone dresses to the hilt. The only Crystal cruises that tend to be slightly more casual are the ones to Alaska.