My DD and I always wear full length evening dresses on formal night. This year she bought a very pretty cocktail dress for semi-formal night, but I have another full length dress I am wearing. It is my only chance to dress up like a grown up!
My husband has always just brought his dark gray suit and dress shirts, dress shoes and ties. This year, however, I am thinking of surprising him with a tux rental because I know he will look super and I haven't seen him in one since our wedding (and since we are celebrating number 26 on this cruise, that would be nice).
Of course, tropical night was khakis, tropical dresses and shirts and sandals.
The other nights, my DH wore very nice sport shirts and slacks, my daughter and I wore short sun dresses or nice pantsuits.