We had a very special dinner at Riad Kniza, but stayed elsewhere. There are many formula dinners in Marrakech, but the quality and professionalism of the staff was second to none.
*Note: google maps has an incorrect location for this property!!! We got quite lost among crumbly ruins and quiet residential corridors by way of our iPhone. The riad's staff told us that they have tried at length to get Google to resolve this. If you ask for directions, beware of false guides, who were particularly aggressive in this area.
All that being said, once you enter the Riad, everything is splendid, and worth the walk.