If you're looking for a meeting place or a good stop around ½ or halfway between Bou Saada and Bab Ezzouar, you can try Sour El-Ghozlane, Algeria, which is about 1½ hours northwest of Bou Saada, or about 2 hours southeast of Bab Ezzouar.
About ¼ or a fourth of the way, you can stop at Ain El Hadjel, Algeria. This is almost an hour northwest of Bou Saada.
About ⅓ or a third of the way, you can stop at Sidi Aissa, Algeria. This is a little over 1 hour northwest of Bou Saada.
About ¾ or three fourths of the way, you can stop at Lakhdaria, Algeria. This is almost 3 hours north of Bou Saada, or almost an hour southeast of Bab Ezzouar.
If you drive straight through without stopping at all, the total distance is 253 km. 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 3 hours, 37 minutes.