We are going to Disney on Friday with park hoppers. My sons are 19 and almost 15. I have no problem letting them go to different parks together but am wondering at what age you would let them go separately? I doubt they will stay together if they head to a different park on their own. They have very different tastes and don't get along that great. Obviously I am not worried about the 19 year old. What about the almost 15 year old? Opinions? Experience? TIA.