From my past experiences I have seen children follow the ships dress code. Often children will dine with their Ocean Adventure group, but if they attend dinner in the dining room I have seen ,and have dressed ours accordingly. Slacks and a polo shirt are quite accecptable for a casual dinner. A shirt and shorts or bathing suit covered up is also the norm for Windjammer /Johnny Rocket luncheon, or for circulating around the ship. Bathing suit attire alone is normally seen only poolside. Formal nite is a great time for a family photo with everyone dressed up in fine cruising style. Our children enjoy the idea of dressing up for dinner with the adults, especially our 8 and 10 year olds who think they are teenagers already, Plus it's a great opportunity to allow them to learn basic ettiquite lessons on dressing, dining, ordering multiple courses from a menu etc.Happy Cruising.