San Francisco has a good transportation system but it depends where u are staying. If you are staying in the San Francisco not a surrounding public transit is good just get Routesy if u have a iPhone or use the site NEXTBUS (http://www.nextbus.com/predictor/stopSelector.jsp?a=sf-muni).One last thing is if you will be visiting other cities in the area get a car you'll die on Amtrak it works but on its own time and is not fun for a vacation, other then SF California is a car state (not an absolute).