From a combox below, for those who have attended a World Youth Day, there is a survey here.
I attended Toronto with a group of nine teenagers and a fellow adult (who just became a mom for the second time!) chaperone. It was a great experience for me as I was preparing to head back to the seminary for my last two years of formation. I think the teens that we took were also opened to the universality of the faith. I found it interesting that during the week, the chants of the teens changed. At the beginning of the week, it was all either state or local chants, by the end of the week, they had become Catholic chants, proclaiming the Truth of the faith. It was wonderful!