The most important variable is direction. Ask any riad which compass direction their terrace faces — east for sunrise (useful if you are an early riser and want to photograph the medina waking up), west or south-west for Atlas views and the classic Marrakech sunset. Most booking sites do not list this information; a quick email before booking will tell you whether the money shot you have in mind is actually possible.
Neighbourhood shapes the rooftop experience as much as the terrace itself. Mouassine and Bab Doukkala feel cosmopolitan and walkable — you are close to the best restaurants and the Bahia Palace, and the rooftop has a mix of local and tourist roofline below. The northern medina around Zaouia Sidi Bel Abbes is quieter, more residential, and feels more authentically Marrakchi — but you need to be comfortable with longer walks through narrow alleys after dark.
If the Atlas view is the deciding factor, book for October through April, book a south-facing terrace, and aim for an early-morning breakfast slot. By 10 am on most days the haze builds. The windows between 7:00 and 9:00 am on a cold clear morning in January or February are when the mountains look closest — a thin bright stripe of snow 70 km to the south.
Navigating the medina and understanding which neighbourhood suits which travel style is genuinely easier with a knowledgeable local guide. A private guided orientation walk on your first morning — taking in the souks, the major landmarks, and a couple of terrace viewpoints — makes the rest of your stay make sense. It is one of the things a good private tour operator does well.