If you're looking for a meeting place or a good stop around ½ or halfway between Erie and Sarver, you can try Clarks Mills, PA, which is almost an hour south of Erie, or about 1 hour northwest of Sarver.
Other possible places to stop near the midpoint include North Mills, and Nesbit Corners.
About ¼ or a fourth of the way, you can stop at Meadville, PA. This is about half an hour south of Erie.
About ⅔ or two thirds of the way, you can stop at Drake, PA. This is a little over 1 hour south of Erie, or almost an hour northwest of Sarver.
About ¾ or three fourths of the way, you can stop at McConnells Mill, PA. This is about 1½ hours south of Erie, or about half an hour northwest of Sarver.
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, 56 minutes.