There's only one SA borders that I know of; one got closed down within the past year. Huebner/I-10 is the open one.

I know several datacenters are in San Antonio. MSFT, Rackspace, etc. Also, the NW side has a medical center, a university, and several banks (USAA's HQ is a mile away from it).

In short, the NW side is an affluent area.