The Riad Mariana was recommended to us by some friends and I can't rate it highly enough. The riad itself is cool and peaceful with plenty of space. We stayed in the Sultana suite which was very quiet despite facing onto the "road" and had a great bathroom (although it was a little dark). We had a great start to the day with breakfast on the roof terrace which has lovely views. And a beer by the small ground floor plunge pool was very welcome after a day in the souks. We also used their hamman offering which means you don't need to leave the riad but you probably do miss out a bit on the atmosphere.
Philippe and his staff couldn't do enough to make us feel welcome and we really felt as though we were staying in someone's house.