Ahoy Jason!
It is great to hear from you! You will love either cruise because fleet wide Disney Cruise Line excels in their service to their Guests. My family enjoys spending time on Disney's private island, Castaway Cay so I know you will won't be disappointed with a cruise that stops there. Also, the cruise out of Miami is on the Disney Magic which will undergo a re-imaging in the coming weeks. The
enhancements will include the youth spaces which your three year will be able to experience. With that being said, I just cruised on the Disney Wonder this past week and always love having seven days to enjoy the ship and many ports of call. If you are having trouble with your decision, I would take price into consideration as well as ease of travel to either Galveston and Miami from your home state. Something else to think about are the Port Adventures. If you think you and your son will venture ashore, the cruise out of Galveston may provide more options.
I hope I've been helpful, Jason. If I can assist you further with your plans, please let me know!
Have a magical day and good luck with your decision!
Nancy