We did receive a refund of port taxes for skipping Costs Maya, I believe $19.95/person. Also, any venue that usually is closed during port days was open. I believe they also may have added some trivia events.
There are two formal nights. Many people dressed up and many did not. Your group would feel comfortable whatever you choose to wear. There is also a 70s night which is quite fun. Lots of great costumes; there was a group dressed as the characters from Scooby Doo and lots of hippies. There is also a “white night.”
If your group is interested in shows and other events requiring reservations, try to make them online; however, if they show “sold out”, don’t despair. When you get on the ship, there are venues where you can still reserve the shows; just be sure to do it the first day!
Happy cruising!