Everyone chooses their cruise for different reasons. We tend to pick the itinerary first. Just because the Jewel and the Dawn are older ships doesn't make them bad choices. Take each of the three and list what each has to offer in the way of on board amenities and their itineraries, and decide what appeals to you the most. You may have to do a little compromising if you can't get everything you want in one cruise. But that will give you a good excuse to go on another one.