If you're looking for a meeting place or a good stop around ½ or halfway between Detroit and Marysville, MI, you can try Anchor Bay Shores, MI, which is about half an hour northeast of Detroit, or about half an hour southwest of Marysville, MI.
About ¼ or a fourth of the way, you can stop at Roseville, MI. This is about 14 minutes northeast of Detroit.
About ⅔ or two thirds of the way, you can stop at New Baltimore, MI. This is about half an hour northeast of Detroit, or about half an hour southwest of Marysville, MI.
About ¾ or three fourths of the way, you can stop at Casco, MI. This is almost an hour northeast of Detroit, or about 14 minutes southwest of Marysville, MI.
If you drive straight through without stopping at all, the total distance is 55 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 54 minutes.