In response to an inquiry about timed tickets:
I recently visited the U.S. Holocaust Museum in Washington, D.C., whose
system of timed tickets seems to work very well for the record crowds
they have received.
 
The only problem that may occur for your visitors, is what does a patron
do if the entrance time on the ticket is for hours later? Is there shops
and/or restaurants to browse through?
 
Hope this helps!