Originally Posted by You
What shoes do you wear most and in what areas of the ship? Would you wear flip flops to dinner? I'm not talking about the plastic ones you'd wear to the pool, but nice ones, maybe with a sundress.
Shoes of a dress style are generally appropriate for "casual" evenings.
Most ships have at least one lounge with live music for dancing, and many ships also have about a half hour of dancing in the show lounge before the show. Thus, you probably will want shoes that are suitable for dancing (that is, a dress style with leather soles rather than rubber soles) unless you absolutely, positively don't like to dance.