here is a listing of many major schools sping break schedules. http://www.tripsmarter.com/panamacit...sbcalendar.htm

The peak seems to be this week and then winds down. Of course, many elementary/secondary schools then have their own April vacations and in early May most colleges get out and then the shoulder season in May and early June. it has been my experience that summer pricing usually starts June 7-8, or so, but I have found $500-600 BOS - Europe in late April- early June. ORD prices may be higher.