Welcome aboard, Jamie! My family and I really enjoyed our two sailings out of Galveston, Texas with Disney Cruise Line. It's a great homeport with a beautiful beach town to enjoy the night before setting sail.
Disney will be sailing out of Galveston through December of 2015, ending with the Wonder's last sailing from Galveston to San Juan, Puerto Rico in early January of 2016. After that, the Wonder will be using San Juan as its homeport for a few special Southern Caribbean sailings for the rest of January before heading to Miami as a regular homeport in February.
Since Disney Cruise Line's itineraries have only been released through spring of 2016, we don't know yet where the ships will be journeying in the later part of 2016. Hopefully the Wonder or Magic may be back in Galveston later on in the year, but I don't know just yet.
If the itineraries are released along the same time frames as they were last year, I'd expect to see the summer 2016 itineraries come out in just a few months, maybe March, and the fall and winter 2016 itineraries released after that. Keep an eye on the
Disney Parks Blog and Disney Cruise Line's Facebook page, as these are two of the first places where you can read about the newest itineraries when they are released!
Have fun planning, Jamie!