If you're looking for a meeting place or a good stop around ½ or halfway between Ashburn and Hershey, you can try Bullock, MD, which is about 1 hour north of Ashburn, or about 1 hour southwest of Hershey.
About ¼ or a fourth of the way, you can stop at Frederick, MD. This is about half an hour north of Ashburn.
About ⅓ or a third of the way, you can stop at Koblan, MD. This is almost an hour north of Ashburn.
About ⅔ or two thirds of the way, you can stop at Guldens, PA. This is about 1½ hours north of Ashburn, or almost an hour southwest of Hershey.
About ¾ or three fourths of the way, you can stop at York Springs, PA. This is about 1½ hours north of Ashburn, or about half an hour southwest of Hershey.
If you drive straight through without stopping at all, the total distance is 115 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 2 hours, 9 minutes.