I have several suggestions.

On a weekend, Saturday mornings at the Ferry Building Farmer's Market are a treat. Snosh your way through the organic specialties, eat at one of the outdoor stalls, or for something different, eat at The Slanted Door (impossible to make reservations at, but showing up on-site can work out well...).

From there, take a ferry across to Sausalito--the ride isn't as long as it is if you do the 1-hr harbor cruises from the Wharf, but the views are just as good. Meander around the shops and views at Sausalito, maybe stay for dinner.

If you go to Wine Country, be sure to drive along Silverado Trail in Napa (more scenic than the main route, and runs parallel to it); and, take highway 12 through Sonoma for some pretty views.

The Charles Schulz museum in Santa Rosa is a good stop fo Peanuts fans.

On Sundays, take a stroll along Embarcadero to Townsend Restaurant for a nice brunch--they're always packed, though, so earlier is better here, too. Tip: If you just want their breakfast eats, go on a weekday morning--much emptier.

For the total meandering experience, get a rental car and drive along SKyline Drive instead of 101 or 280...it's quite different, and has some beautiful mountainous views.

I'm sure I could come up with more if asked. PM if you'd like.
M