We just got off the Caribbean Princess and saw very few people in jeans at dining restaurants. They really do try hard to make the experience nice and the set up is a nice restaurant and the wait staff is dressed nicely. Most all the ladies were dressed in dress slacks or sundress, or skirt. Men in polo type shirts and no jeans. You can wear the same outfit several times, especially if you change up the top. We dressed for dinner, then came back to our rooms and changed for the evening. I would definitely feel out of place wearing jeans for dinner.