Oakland (OAK) and San Francisco (SFO) airports are roughly the same distance from Sebastopol. If you don't encounter traffic, the drive takes about an hour and a half.
Oakland is smaller and easier to deal with. More flights come into SFO.
If you're coming from LA, Las Vegas, Portland, or Seattle, you can now fly directly to Santa Rosa (STS), about 20 minutes from Foo Camp, on Horizon.
Next best option is the Sonoma County Airport Express, which runs every hour from SFO and every two hours from OAK. Get off at the Days Inn in Santa Rosa, and take a cab (about 20 minutes) to Foo.