http://www.flyertalk.com/forum/briti...ook-today.html
This thread from a few months ago has some good info on Marrakech.
3 days is probably just right for RAK:
If it were me, I'd probably take a pretty relaxed approach to the days - just take a couple of good books to read over a few glasses of mint tea on the roof terrace of a riad. If you prefer something more active, you could take a trip up to the Atlas Mountains or maybe across into the Sahara.
The city is at its best in the evening. Most of the action is centred on Jemaa el Fna (the main square) and surrounding souks.