I always recommend 0one's Blueprints. They are all great! Now the Great City is being turned into a full color campaign setting coming out in September. All of the maps that relate to the Great City will be useful for player handouts.
The "Saltshacks" is a useful tool for developing a city area/community built on boats. Many a good dock chase could take place here. Remember, this is only a specific (and perhaps limited) portion of a city.
This is a product of related maps with a few suggestions on how to use it. The maps are waiting for you to fill in the details and provide them purpose. Of course, you don't need to render the maps! The maps are rendered in "old school" blue line style. Options are also available.