CVC 40502 states:
40502. The place specified in the notice to appear shall be any of the following:
(a) Before a magistrate within the county in which the offense charged is alleged to have been committed and who has jurisdiction of the offense and is nearest or most accessible with reference to the place where the arrest is made.
(b) Upon demand of the person arrested, before a judge or other magistrate having jurisdiction of the offense at the county seat of the county in which the offense is alleged to have been committed. This subdivision applies only if the person arrested resides, or the person's principal place of employment is located, closer to the county seat than to the magistrate nearest or most accessible to the place where the arrest is made.
40502(b) doesn't allow you to choose any county you want for your trial -- it only allows you to request the county seat within the county where you were cited, and then only if you live/work closer to the county seat than you do to the nearest courthouse from where you were cited.