BENSI'S
BAR MITZVAH

Healdsburg is easiest to get to and from if you can find a good connection to STS, which is just 15 minutes north of the synagogue and 15 minutes south of the campground.  It is a small airport, with few connections, but is quick and easy to fly in and out of.

SFO is about 2 hours away without traffic and is a major hub with many connections.  You can rent a car from there or take the Airporter - a shuttle that will drop you off at STS or in Santa Rosa.

OAK is roughly the same distance and is a Southwest hub.  Other than that, SJO and SAC are options, but further away.

Uber and Lyft are good options in Sonoma County, though more rural areas may have poor or no service, especially on weekdays.