This website can help you find the hotspots with the greatest number of species reported.
On the home page there are links to the 25 locations in Ohio with the most species reported.
On each county page there are links to up 10 of the hottest locations in the county with over 100 species retorted. Examples from a couple counties are below.
While not exclusively visits to all the top hotspots, the Ohio Birding Drives visit some of the best locations in each county in Ohio. Many counties have two or more suggested driving tours that can be done in one day. When you are out and about in parts of Ohio new to you, these birding drives can lead you to good birding locations.