We stayed 4 nights in Marrakech. Did a walking tour with a guide suggested by our medina to get to know the area and see some of the highlights. Don't miss the Koutoubia mosque, La Bahia Palace, El Badi palace, saadian tombs, and Jemaa el Fna at night. We did a cooking course with Marrakech Faim d'espices, which was fantastic. Otherwise just spent time exploring the city, enjoying the night life in Jemaa el fna, and trying out all kinds of tasty foods.
I went there solo in December to Marrakech once and loved it so much! Definitely would stay in a Riad again, the Souk area is nice for that. In the center of the Souk is a nice square with lovely rooftop restaurants to enjoy the sunset. I also visited a Hamam. It was called Lotus Privilege, it was my first hamam experience so can't compare, but it was good! And visited Majorelle garden.. I walked a lot in Marrakech and took a bus once. Would love to see more of the country.