I'm not sure about the parks being run over with teens. I doubt it though, I bet they don't come until night.
Just make sure you see Fantasmic on one of the nights they are open late. We only have one chance, so I am crossing my fingers for the balcony seating. Also, there is no Electric Parade, which I am absolutely devastated about. DCA closes at 8:00 every night that week except for Friday (which we are leaving). I thought going so late in June, we would be able to catch all the shows, but I guess not.