Oooo... I'm already doing this concept for a game I run. In fact, I posted the before map here last month. Check it out here: http://www.cartographersguild.com/showthread.php?t=6258
Now that the Oten-Jo challenge is over I'm planning on finishing up the current map of what was once called Taristal, but is now called Shardport. I'll post them both together when I'm done.