We went on the free walking tour of the bridge and it was fascinating. Though there are many informative boards at the Plaza on the SF end, we gained so much more by having a local tell us all about it. Thank you, Dan.
PS Beware of the cyclists. As our guide said they are either serious pros who don't like meandering tourists or people who have not been on a bike for 20 years and who have just hired their bike 10 minutes ago !