Ally, San Fran.
Do a trip round the southern end of the north bay. Take the Bay Bridge to Oakland - foot down and drive through quickly - then up through Berkeley (Uni City) and Richmond and then over the San Rafael bridge to San Quentin (the prison). Come back along the coast via Sausalito (big marina, big yachts) to the Golden Gate and the Presidio (big parkland) - about 45 miles.
Then get your walking boots on. 125 miles east gets you to Yosemite NP, the Sequoia forest and the giant redwoods. You can yomp free or join a guided tour - well worth it. Avoid Oakland, Fremont and San Jose. O and F are dumps and SJ is super expensive - Silicon Valley and all that.
BTW if you want a KFC don't expect 'fries' it's mash and gravy.