Originally Posted by malsf1

My suggestion would be to pay for your Bart ticket from SFO to your first destination. If you are near a Walgreens, you can get a card and add whatever value you want. I have one card with a monthly "A" pass for work, and another with cash value that I use to go to the east bay each week. If you do add value on line, the website warns that it could take 3-5 days to add the value (this is, IMO, the only bad and poorly planned part). Otherwise, you can instantly add value at most Bart and/or Muni stations.