I experienced my first Coastermania in June of this previous year.
The number of people was fairly overwhelming, I didn't expect that there would be that many people there.
If you have the time, spend a day two at the park beforehand, the crowds are light.
If I remember correctly, ERT lines were about 10-20 minutes, and were much less on the Thursday preceding Coastermania.
It is pretty cool being in the park at 7 in the morning, up until 1 the next morning. The food wasn't bad either (but of course we had the muffleheads :) )
I posted a short trip report:
http://www.zoomnet.net/~bmgain/Feature/TR/coastermania.htm
-------------
Tyler Adams
Cedar Point Web
http://www.zoomnet.net/~bmgain