i actually had my grad nite there, as have my niece and nephew. i think it is only area schools, but i could be wrong. i don't think it has a huge effect on hotels because the kids are bussed in and the bussed back home in the morning.
we're scheduled to be at DLR june 9th - 13th, and i'm hoping crowds will at least be somewhat lighter than they were in mid august of last year. i'm also hoping for some good, solid "june gloom"....i'm tired of being at DL when it's miserably hot, lol!