IN Marrakech or OUTSIDE Marrackech?

If you want a riad inside, then Villa Des Orangers is one of the best bets. Others get mentioned in the same breath, but I've stayed at VdesO and can highly recommend it. Location is great and you get airport transport, breakfast, lunch, mini-bar and laundry for free.

Outside town, you've got the Aman plus a number of other places of varying quality. As long as you avoid the Palmerie Golf Resort, where I went for a conference a couple of weeks ago!

Personally, I would do a couple of days at a riad in the centre like Villa des Orangers and then a couple of days in a property outside the city. This will save you the hassle of driving into and out of the city every day - you can dedicate those days to sunbathing or mountain activities.