We did a day tour out to the Ouzoud waterfalls. The driver and guide were ten minutes early, and then we were off. It was really worthwhile to have a private tour, and to have something organised from this end before you go. (Youseff is very good at getting back to you by email to organise it all before you set off). I paid a deposit by Paypal, and paid the rest at the end of the tour. Nice and simple. Dirhams or Euros are fine.
The trip is long, but definitely worth it when you get there. We trekked about, had something to eat, and then when we were done, we found them and we could go back home. SO nice not to have to wait for a busload of lemmings to finish.
Our guide Ismail was very chatty and taught us a lot about how Rammadan works and the Berber people. On the way back I think we all dozed a bit (apart from the driver!!). We could stop to take some pcitures of things that grabbed us on our way (so a cattle bartering market, or a french fortress). Nothing was too much trouble. Ismail's English was excellent.
The driver didnt speak much English but he seemed obliging enough.
It might be pricier than arranging a cab to take you there and back, or to do a bigger tour group. For us, though, this was totally worth it.