Can I automate location changing so I don't have to drive the choice manually?
AirPort Location** takes snapshots of the system settings you select and re-applies them the next time you use your machine at that location.

** Update Oct 2016: Airport location appears to be no longer maintained, but still available at [MacUpdate.com][2]. It may be limited to older versions of OS-X. The same site suggests [ControlPlane][3] provides similar functionality; I have not used it.