Your city sounds interesting, it reminds me a bit of the city of Neverwinter (from Neverwinter Nights 1&2). It also has the district thing going on.

As a practical matter, are you aware that if you are going to put a 6 mile wide city on a 24 inch wide map you end up with about 1300 feet per inch? Houses would probably be too small to be displayed like in the map you provided a link to. Maybe a smaller city would be more feasible?

Hope you can find someone to make this for you!