I'd spend as much in gas roundtrip to butler Co as I would parking at the Banks. I don't think a few bucks to park, especially during the holiday season, is a measurable deterent.
I'd say geography is more important. where do most of the potential attendees reside?
If this is an event for younger Alumni you need to be closer to downtown. If this is for older alumni and families then by all means to Fairfield.
I've been to some pretty heavily attended watch parties around Oakley. The Oak Tavern has hosted in the past.
If we want to do the Banks I would recommend Yard House over Moerlein though.