Category N is farther away from Category M, and is located in the forward section of the 4 deck, outside the medical center. While low in the ship you will be on a floor with limited other cabins, meaning less crowding. And using the elevators will be quite easy. While not guaranteed, you will possibly be upgraded if the ship is not sold out. I sometimes prefer an inside room, sleeping is best in total darkness, if you sleep late you won't be bothered by sunlight.