In the Cleveland area I would recommend looking at Cain Park or Porthouse.
With Cain Park in addition to theatre you can also get a glimpse into running a concert venue/road house, as well as Arts Fest. The current general manager is a former stage manager for David Copperfield so you can definitely get some stories and lessons from her experience with him.
Porthouse does three shows a summer and is a branch of Kent State's theatre department. They operate under the URTA contract, so it will be a mix of Equity actors and students, and you will be working under an Equity SM.
I've done two separate seasons at both theatres (99 as an intern and 03 as an assistant production manager/events SM for Cain Park; 04 and 05 as an Equity SM at Porthouse) and had some great times with both companies.