We would like suggestions for guide service for a day trip from Rabat to Chefchaouen Morocco in late April.
KF
This would be a very long day trip - probably 8 hours in a car, so not much time there. If you have time, perhaps you could go there one day, spend a night, and then come back.
If you are interested in visiting something similar to Chefchaouen, in Rabat itself you could go to the Kasbah des Oudayas. Two hours from Rabat, I can recommend the beautiful town of Asilah. Chefchaouen as a day trip makes more sense from Tangier if you will be there as well on your trip.