If you purchase the REAS package, I believe you can also choose your dining rotation. However, IMHO, the dining rotation shouldn't impact your decision to go to formal night or pirate night. All restaurants are just as nice.
We were in Parrot Cay for semi formal and formal nights this past October. The colors of the restaurant seemed to be brighter with all the dark colors of the formal attire. Most people don't like this rotation, but it was just as nice for us.