A cruise has more dress codes per day than almost any other holiday, which makes it a better premise than a beach.
Morning on deck, afternoon in a port, evening at a formal dinner, and theoretically all of it packed into one case. Treating it as separate outfits works. Treating it as a wardrobe, where pieces reappear in new combinations, is more interesting and changes which items you reach for first.
Several princesses to dress, which means the group has to hold together at dinner as well as individually.
Fairytale Heroines Dress Up 
Lady Jane