Hi Jason,

Depending on the Features and the concept you're thinking of putting together...

You may want to checkout the following Directory Scripts...

Some Excellent Free Software I've posted about in other threads with added Pay for Features if required...

http://www.onlinemarketingtoday.com/software/
http://www.boonex.com/products/barracuda/
http://www.freephpdirectoryscript.com/

Regarding CityAmerica...

It's probably Best to review just how many are Actually running and Marketing the Portal as a Real business...

And contact and interview some to get a True picture...

As far as getting mass Local Traffic...

Just like with Any other business... Marketing, marketing and more Marketing...
http://www.cityamerica.com/pages/CityDirectory

Keep in mind, there are Lots of poor quality Local Portals...

But Googling and researching Local brings up some Great Directory models...

Phil