There is an address locator that is supplied with Business Analyst that can be used to geocode only city/state locations. Open the address locator manager and click the add button to add a new locator. Navigate to the following location C:\ArcGIS\Business Analyst\US_2012\Data\Geocoding Data. There you will see a city/state address locator that can be added and used for geocoding. Remember you must have Business Analyst installed to use this locator. Also the directory will be different if a default install was not conducted.
Scott.