I would really recommend working as a camp counselor (overnight). It has many experiences that would transfer working onboard a ship (woking with kids in a similar age bracket as on the ship, living and working with other staff - some who may be international, working long/irregular hours, working outdoors in heat, being away from home/family).
DCL does not require (at this time) a college degree - just 2 years experience working with kids. Some other cruise lines do.
So if you do decide to go to college it does not matter what degree you get for DCL. If you are looking for something that would complement the job - Child and Youth, Education, travel/tourism, recreation and leisure studies, or even theatre would help.