They really don't like having cameras pointed at them over there.
I'd take the 15mm so you can hipshoot when need be. Alternatively something longer like a 90mm if you have it. Use a 35mm and you'll get caught.
, on Flickr
See the second guy on the left and the others on the right giving me the look of death.
I walked away with them shouting at me. Many folks want money for a picture, but I get the impression the guys who wheel the barrows around the Medina are a particularly grumpy bunch and don't like tourists.
ETA. If you're spending all your time in the Medina bring plenty of changes of clothes. In just one day you will reek of raw meat, spices and effluent. I kid you not!
Taking pictures there is not easy. You have to keep moving or the hawkers will be all over you and you won't get a shot anyway. It's a tiring but exhilarating experience.
Oh and you'll need eyes in the back of your head, so you don't get run over by a scooter or an donkey!