Best way to pull regional leads?

Are these inbound leads to your website? Or more specifically, do you have inferred data for these leads? If so, you can use the Inferred Metropolitan Area filter. The San Diego and Los Angeles values in that filter should cover most of SoCal.

Jenny, this screenshot of a Smart List might help. I just ran a report to show me all of my leads in the NYC region. You'd want to make sure your filters are set to ANY.

I've run lists like this to promote events to everyone local to a specific area.  My method was similar to Adam's above, I just used different fields.  Setting the filter logic to ANY, as Adam mentioned, I simply looked up lists online of all the zip codes and area codes of the region I was promoting to, and pasted the whole list(s) into:
- Inferred Phone Area Code
- Postal Code
- Inferred Postal Code

You could of course use the State and City abbreviations in addition to these; I just found I didn't have to deal with guessing weird spelling variations of cities/states when dealing with numerical codes instead.