There isn’t much to do in Chefchaouen, other than admire the lovely blue color painted on many buildings. There is a mosque that can be visited after an uphill walk, a waterfall, and a walk downhill from the waterfall along the wall of the medina. You can stroll in the medina admiring the walls, having lunch or a coffee. There is not a lot on display that cannot be purchased in other Moroccan cities, but Chefchaouen is an enjoyable place to stop and stroll.
We made our visit as a day trip from Fez. I don’t recommend it because it is a long day in the car. Much better to stay overnight nearby or to combine a visit to Chefchaouen with a stop in one of the coastal towns nearby, like El Hoceima.