Although I have never sailed on NCL before (my first NCL cruise is in 30 days!), I can tell you from my past cruising experiences that you cannot go wrong with a balcony room! Just make sure that you do not have an obstructed view. Also, since this is your first cruise and you don't know if you will experience any motion discomfort, you would probably be best to pick a room near the center of the ship rather than the front or rear. I actually prefer to be on the higher decks, but I have heard it said that there is less feeling of motion on the lower decks. I also am careful to choose a room that is not directly under a public area such as a restaurant or entertainment facility.
Hope this helps you some...Happy Cruising!