The medina of Essaouira is a magical place. It combines the best of Moroccan Medinas and of Mediterranean coastal villages. The white-washed Medina is decorated with bright blue doorways and windows and many of the streets are painted different colors, with each alleyway leading off to a new nook to discover. It's not all that big and you can see it all in two full days (that is, if you're busy. I could spend weeks just lounging around Essaouira!). There are two or three main streets which intersect at the souk area in the middle. You can walk to pretty much anywhere in town in about 20min.
My favorite thing to do in the Medina was just wander through the various neighborhoods, admiring the ornate and evocative doorways, exploring the winding alleyways in the Mellah (but don't go at night!), and simply following my way around the city walls.