Dar Si Said was a genteel riad in its day and still maintains its stately grandeur, although it's now home to a museum of Moroccan traditional crafts. It has displays on everything from cutlery to carpets to traditional Berber jewelry, an exhibition which was accompanied by old photos where where particularly interesting. To be honest, the museum part isn't that amazing, and many of the explanations are in French.
What is worth the visit, though, is the building itself. It's in the same league as Ben-Youssef and the Bahia Palace in terms of intricate craftsmanship, mind-boggling detail, and beauty.