Hi David, Mine was only a short trip - 5 riding days - but did the following:
Day 1 - Marrakech - Tiz n Tichka Pass - Ait Benhaddou
Day 2 - Ait Benhaddou - Ouarzazate - Boumalne Dades - Dades Gorge to Msemir - Gorge to Gorge piste to Tamtetoucht - Todra Gorge
Day 3 - Todra Gorge - Tinerhir - Tinejdad - Erfoud - Rissani - Hassi Labied (Erg Cherbbi) - Merzouga
Day 4 - Merzouga - Rissani - Msissi (on N12) - Piste from Msissi to Zagora
Day 5 - Zagora - Ouarzazate - Tiz n Tichka Pass - Marrakech.
The 2 piste routes we did are covered in Chris Scott's Morocco Overland.
The Gorge to Gorge is route MH3, It's about 45km and can be tricky as parts get washed out. November was no problem other than it being very rocky in places, but going at Easter you will be following the winter then spring thaw and it can be made impassable in places. Tim Cullis is the man to ask about this route - he's done it several times. It's a fantastic route, but can be challenging! The second piste from Msissi to Zagora (Route MS4/MS2) is longer (about 160km) but technically easier - desert riding on the flat, mostly dusty tracks, some sand, a few villages to pass through. There's a filling station at Msissi, just before you turn off the tarmac and pick up the piste - fill up there and you'll make Zagora without needing to refuel.
Have fun!
