We have let our 3 ds go off by themselves but they must follow our family rules, staying together in the same place, not leaving without all 3, using their room keys to charge only acceptable things like food, or an inexpensive souvenier etc. They have never disappointed us and always arrive back at the curfew time etc. Our ds are 16,14 and 12. Just set limits and let them know what is and is not acceptable and that this is a privlege they earn, not a right!