Oh my, I just completely teared up reading about your son crying after leaving the lab. On our FIRST cruise, 4 days on The Wonder, my then DS9, did the same thing. Only it was after we checked into our day room at the Hyatt at the Airport. Walking to the room he stopped and was crying. It broke me down too! He said it was the best vacation ever and he missed everyone - the counselors, his new friends.
We reminded him, we rebooked on board and he spent the next year moving a penny from one jar to the other.
Awww, what a wonderful trip report!