In reply to Arkel:
Marrakesh isn't that bad, you'll be past the worst of it in the first 15 minutes. If the sat nav tries to take you along Rue Bab El Arhdar, change it before setting off to go around the north of the city on the larger roads instead. It is quite manic in places with scooters, bicycles, camels, horses, people stepping out into the road in front of you but in the very centre you can't go that quickly anyway.
The rest of the drive is much easier. They're rebuilding the N9 at the moment, and the bits they've finished are much improved. It is still a long drive, realistically 8 hours - there are places to stop all the way, I find Tizi n'Tichka and Skoura convenient. I would try to get to Skoura in the light if possible, nothing difficult after that. The roads in the Atlas had quite a bit of snow a few years ago in February, and they are quite twisty, so watch out for that.
Last time, we drove down to Merzouga for a rest day. I was worried it would be a bit of a push at 3 hours each way, but a very easy drive on wide, quiet, straight roads and was well worth doing.
I have driven a few times, and think it's handy having a car to reach upper gorge.
Post edited at 21:11