Just saw this... hope you haven't left yet!
I was on the Dawn a year ago, and I have some comments. First.. I really enjoyed the cruise.. however, I felt the ship was too big. I prefer smaller ships, but that's just a personal preferance.
The crew went out of their way to help us. They were always very pleasant, always made the effort to smile and say hello. I appreciated that.
The food is fabulous. I would suggest you go early for dinner, or you'll have a long wait. We never waited when we arrived before 6pm.
As for the excursions:
We went to Cape Canaveral and really enjoyed that! Been to Disney a bizzilion times, so that didn't interest me.
In Miami, we did that bus trip where it takes you to the shopping center and the beach. It was very cold when we went and started to rain, so the beach was literally a washout. But, if it had been nice weather, it would have been wonderful.
We hated the private island because it was more crowded than on Coney Island during Labor Day. Wall to wall people. AWFUL! I would you suggest you make sure you're on the first tender out there.. grab a chair and hit the ocean before the cattle call begins! Then, swim and go back to the ship.
Nassau was fun. Definately tour Atlantis (you can do this on your own)-- and pay for "The Dig" tour when you're there. Amazing aquariums. We liked Atlantis so much, we went back on our own for a week! Only hotel guests are allowed to use the water park, but if you pay for The Dig tour, you can use their private beach.
The Dolphin Encounter is a must do! That was the highlight of my time in Nassau. I did this when I was staying at Atlantis, not when I was on the cruise. Don't know if you'll have time to do both.
Enjoy! Tell us how you liked it.