If you're looking for a meeting place or a good stop around ½ or halfway between Detroit and Findlay, you can try Toledo, OH, which is almost an hour southwest of Detroit, or almost an hour north of Findlay.
Other possible places to stop near the midpoint include Bolles Harbor, Avalon Beach, Vienna Junction, and Luna Pier.
About ¼ or a fourth of the way, you can stop at New Boston, MI. This is about half an hour southwest of Detroit.
About ⅓ or a third of the way, you can stop at Monroe, MI. This is almost an hour southwest of Detroit.
About ⅔ or two thirds of the way, you can stop at Perrysburg, OH. This is a little over 1 hour southwest of Detroit, or about half an hour north of Findlay.
About ¾ or three fourths of the way, you can stop at Bowling Green, OH. This is about 1½ hours southwest of Detroit, or about half an hour north of Findlay.
If you drive straight through without stopping at all, the total distance is 117 miles. The distances shown above don't include local roads to get into each town, so if you're planning a long road trip, make sure you factor in traffic and road conditions, rest stop breaks, and interesting detours along the way. If you're in a rush, you can do the trip with zero stops, and your total travel time would be around 1 hour, 52 minutes.