switch hitter

What’s the benefits of switch hitters in games? I realize a lot of players can’t switch hit but if you have a switch hitter. How do you use them to benefit the team during a game?

UPDATE: We have found a team, and we are no longer looking. Thanks for all the contacts and info, maybe next season? We just got word that our '04 Club is folding. Our DD is ready and available to fill in or maybe fill a spot. We'd hate for her to not play this summer. She's RH throw with...