Cedar Point recently moved their main boneyard onto land behind "Seville," between the railroad tracks behind Snake River Falls and Millennium Force's two lagoon crossings. They also have some storage space beneath White Water Landing (that seems to be where they store the coaster car cribbing when the cars are on the coasters) and in and around Disaster Transport.
Kings Island has a few items out in the woods behind Tomb Raider: The Big Secret, but most of their stuff is right up front immediately South of the row of buildings along the parking-lot side of the park, behind the tall fence gate at the railroad crossing.
Kennywood's boneyard is on a hill behind the Racer, clear up to the edge of the cliff where you can get a spectacular view of the river.
Finally, Wyandot Lake seems to use the field behind the parking lot, adjacent to the golf course. Oh, and ALL of the Six Flags parks seem to occasionally make use of
the Old Indiana site.
--Dave Althoff, Jr.