Wait! I'm both! Formal for me means nice dress, by which I do not mean spangly prom dress/evening gown, AND dress shirts for men. And a jacket. Hopefully.
I wear a suit every day. If I brought a suit on a cruise I would never go. I am not dying to see men dressed like it's a workday, either.
But I am also and avoid the dining room person!!! If I'm tired from a day on shore I am not going to go to formal night.
It's easier for women. We wear dresses half the time anyway.