Here is a plain answer. We have been on the CP twice in the last two years. In the Main Dining Rooms, one is suppose to go by the Formal Dress Code. Some do not. At the Buffet, which on Formal nights has the same food, except you shell your own Lobster Tails. Smart or Resort Casual is usually the code. Again, some do not. On our first CP cruise we dressed both Formal nights. Last year we skipped the Main Dining Rooms on the Formal nights and wore Resort Casual. Basically, do what makes YOU feel comfortable. It is a cruise, a vacation, have fun and leave the trivial worries behind.