I've been twice on the Navigator last year and numerous times to the Carribbean. I prefer a balcony and we were also in 603 for one of our cruises. There is a downside to that room if you are anchoring, you will have about 5 minutes of clanging noise when they arrive. If they dock, you won't have that. Navigator has two restaurants and pool grill. Food and Service are excellent. You will have a great time.
2 for 1 is a great deal. When you are on board, book another cruise for the on-board booking discount - you will be able to use that for your next cruise.