Left = port, right = starboard ("left" and "port" both have four letters).
Advantages to portside: Faces the sunset at Key West, so you can sit on your verandah and enjoy (and watch all the other boats go by). Once the ship alongside leaves in Cozemel you have a great view of the island. Your required lifeboat drill is on the shady side of the ship if you need to report to Deck 4.
Face it, you can't go wrong as you're on the ship!