I´ve been there with a friend of my for around 12 days. You can see places in the following sequence: Fez, Merzouga, Ouarzazate, Essaouira, Marrakesh. We can also really recommend doing couchsurfing in this country. It was always good experience to meet new people, cause of the culture, religion, mentality and because they only pay half the price a tourist pays
If you have any questions to that trip, just leave a post or write a mail. Enjoy!