The ship does not always back in. Depending on things such as the tide, currents, wind speed and direction, and the captain's mood that morning, the ship may pull straight in. In 7 cruises, we've backed in 5 times, pulled straight in twice.
Anecdotal evidence on the DIS says that the ship is more likely to back in, which would give the starboard side of the ship a view of the beaches, but there are no guarantees. I personally like the port side, so I can watch the ship back in and tie up to the pier. I'm usually on the island all day once they clear the ship, so I don't miss having the view.