I have a hard time with cities, too. NeonKnight recently posted a pretty extensive CC3 city. I think he was using City Designer 2 for the layout, but do a search for Deestan and you'll see it.
If you've got a raster editor such as Photoshop or the Gimp, you might get some benefit from looking at these city tutorials: Koppolex, Gullside, and Eneini. Lessee if I can dig up links...
[Award Winner] A medieval town map tutorial in Photoshop
Detailed tutorial: Gullside
[Award Winner] Eneini: a medieval city tutorial (in Photoshop)