...... she's always stressing out on itineraries for us when we travel. ... and you come-up with this itinerary.!
Effectively you have just 8 days to enjoy Morocco, excluding the 2 days arriving and departing. With such a short time, to avoid stress forget about the long bumpy road trip to the desert, these trips can take 12+hours each way from Marrakech, Agadir or Fez, a full 24 hours out of your short time. The same stress avoiding applies to the proposed slow road trip from Fez to Chefchouen as travel through the Rif is slow and time consuming, you have a mere 8 days to work with.
Arriving at Agadir a day spent here is not a bad idea and gives you time to find your feet before moving on to Essaouira. Spend a bit time in this small picturesque seaside town, a terrific place at night when the hoards of day-trippers from Marrakech leave in the early evening, otherwise it will be an overly touristically experience, two nights here. On to Marrakech, a week could to usefully spent here, (and you don't have a week to spend here) apart from the main tourist stampedes through the Medina and Place Jemma el Fna, the New Town Gueliz is worth exploring, a good place to shop and eat, follow the office workers to see where they go. From Marrakech using the citybus service to explore nearby mountain villages(bus L45) or the Agafa Desert (bus L33)shouldn't strain you...... http://alsa.ma/fr/marrakech and .. http://alsa.ma/fr/marrakech/itineraire-per-urbain
Moving on to Fez by bus or train to Fez and get lost in the labyrinth lanes and alleys and have fun doing it rather than rushing all over the place, spend your time on foot absorbing the experience, better than sitting in a hot stuffy van for 12 hours twice doing a Desert trip when you really don't have enough time.
Try to find good city-guides to Marrakech and Fez before you go...