We’re scheduled for our 14th Princess cruise. The first few, I wore my tux. Then, traveling with other couples, we went with suits. This same group traveled together again and transitioned to sport coats and no ties. The ladies still dressed up but a little more casual. I think cruise location has some impact on how the majority of people dress. A bit more formal in Europe compared to a Mexican Riviera cruise.
Based on personal preference, I stick to the sport coat as an acceptable compromise.