We will be on the Dream a weeks ahead of you. We are scheduled to leave out of Houston, better make sure before you do any bookings for Galveston. The kids will have a blast, lots to do. As for the Kids Crew program, depends on the kid, our last cruise we had 3 of them, 1 absolutely loved it, the others refused to participate. I am sure the 18yr old will be happy to just hang out.