on Ocean Village you can wear what you like - no formal evenings at all. At the upper end of the scale, Princess say, dark suits for men and skirts/trousers for women are fine even for formal nights... nobody gets sent to their cabin for dress code violations that I know of. Colour is fine too, especially in the Caribbean. It's mostly a matter of not wearing beach clothes, as Dassie says; just pretend you're in a nice restaurant for casual nights and a really nice one for formal nights.