The rapid transit system through most of the San Francisco Bay Area is BART, Bay Area Rapid Transit. This will take you from the east bay area into San Francisco, as well as Oakland and San Francisco International Airports.
Central Contra Costa County has a good bus system,. It’s the Contra Costa County Connection
Alameda and parts of Contra Costa County use AC Transit. This bus line will meet up at most BART station in West Contra Costa and take you into San Francisco as well.
San Francisco has a bus system as well. MUNI has a great website that maps your trip and shows you the time it will take as well.
The ferries that cross San Francisco Bay offer business-people and tourists a great look at the San Francisco skyline. You can catch a Golden Gate Ferry and go to Oakland, Almeda, several stops in Marin County as well as Vallejo.
AMTRAK is a great way to see the Western Stares or just take the train to Reno and Lake Tahoe.
If you need a Taxi Cab in Walnut Creek, here are two services that are available.
Walnut Creek Taxi Cabs
A Royal Cab 925-934-3411
Yellow Cab 925-935-1234