It's fine to wear your suit. Formal night consists of a lot of picture oppotunities and usually lobster. We just returned from the Conquest and we were casully elegant. No pictures this time being as it was our sixth cruise. We also enjoyed not feeling like we were missing out by skipping the dining room a couple of nights. Whatever you are more comfortable with is my answer. It's mostly just getting dressed up fro the sake of getting dressed up.