No shorts or jeans for sure. For guys, slacks and a polo or button down shirt are fine. Jackets optional. I wore nice Capri sets most nights.
For formal and semi-formal nights it's as dressy as you want but the guys usually wear a jacket if they don't wear formal or a suit.
For us girls, I wore (basic) black jersey pants and a glittery top for formal night. Others had on evening dresses, coctail dresses or "Sunday" dresses.
If you want to be really casual, you can dine at Topsiders.
Note: no formal night on the Wonder.