Sitting right next to SF city hall, the museum home to one of the world’s finest collections of Asian art. Right now, a beautiful exhibition called teamLab: Continuity is on view. You can become part of an interactive landscape of blooming flowers, darting fish, and soaring crows. Check out this YouTube video: https://youtu.be/-gO8D6Rz2tI A limited number of walk-up tickets are available every hour. If you want to check it out, please head over the Museum right after the ceremony.
San Francisco City Hall is a Beaux-Arts monument that features vast open space, tall dome and exquisite decorations. While you are at it, might as well snap a few nice photos in this historical landmark. Here's a page that has a 3D walk-through of this beautiful building: https://www.iqphoto.com/san-francisco-city-hall-wedding-photographer (scroll to the bottom for the 3D walk-through)
If you want to get a cup of coffee to start the day, there are many coffee shops nearby. My all-time favorite is Philz Coffee is merely 5-min walk away from the City Hall. The address is: 399 Golden Gate Ave.