We had our Hunter 27 at Mentor Lagoons near you for three years. Four hours was a good max for a three day weekend. That's basically From Cleveland to the west to Geneva to the East. Chagrin River and Fairport Harbor are two other good destinations within that range.
Sailing across the Lake to Erieau is 8 to 10 hours. We love Erieau, but would not plan that trip for three days. You have to leave time to wait for fair winds for an 8 hour leg.
If you put in at Sandusky or Catawba Island where we are now, three hours will get you anywhere in the US Erie Islands. Marinas, moorings and anchorages abound in Sandusky Bay, Cedar Point, Kellys Island, and the Bass Islands, including Put-in-Bay.
A good nearby, first cruise would be Fairport to Geneva. Lots of things to do in Geneva, and the Marina is nice. Be sure to tie up a Pickle Bills in Fairport coming or returning.
Start simple, and build up to longer cruises. Most of all, take your time, and enjoy yourselves!