The souks of Marrakech were much easier to navigate than those of Fes. The Rough Guide to Morocco provided an excellent guide to accessing them, and once inside, it's quite easy to find your way. It's also a great place to get acclimated to the noise, smells, and life of the country.
The places closest to the Djemaa el Fnaa are more aimed for tourists. The quality of products was not very good, and the prices were very high. You will have to make your way into the heart of the souks to find items of good quality.
I highly recommend the cloth found in Marrakech. The weave is well done, and the colors and patterns are quite captivating. One of my group members bought a beautiful piece woven of cotton, silk, and cashmere in gorgeous sunset colors that I have not seen elsewhere.
I would not, however, recommend buying many things here if you have a chance to travel to other parts of Morocco. I was able to find things, such as wood, carpets, and pottery, that were of much better quality and price when visiting some of the other cities. The merchants are very good bargainers and start out at often outrageous prices. Even though I already had an idea of the prices being charged in other places, it was very difficult to find a good deal.