From Rissani you can transfer across the desert to Merzouga. You can book a luxury tented camp from where you can explore this magical landscape. There are huge dunes which reach heights of more than 150 feet. You take a camel trek across the desert to watch the sunset and the sand turn a wonderful orange color. You then have dinner under the stars with traditional music. The next morning you have a sunrise trek before breakfast. You are guided by Tuareg nomads who are dressed in a wonderful blue color that they are known for. This was by far one of my favorite moments in Morocco.
Seeing the Great Sahara is one of the 1000 Places to See Before You Die, as found in the book by Patricia Schultz.
You might also check out the trip by Ker & Downey; they’re one operator to check out.
I had two wonderful Moroccan guides; they are Jalil Braoul at email@example.com and Saida Ezzahoui at firstname.lastname@example.org. They are both based in Fez.