Go north from the Golden Gate Bridge on Hwy 101 for about 20 miles. Take the Hwy 37 off ramp. Continue 6.9 miles to Infineon Raceway, turn left onto Hwy 121 (see map below). Drive 6.5 miles to a four-way intersection and flashing red light at the 76 station. Go straight ahead, and after 1.5 m. veer to right, DO NOT take Hwy 116 to left; continue straight along what is now Arnold Drive for 4.8  miles to Boyes Blvd;  turn right then 0.9 mi along Boyes to Hwy 12. Turn right, go 300 yds to 18340 Sonoma Hwy, and right into parking lot just before Thailand Restaurant; please go to rear entrance of single story cream building. (There is an excellent coffee shop "The Barking Dog" 100 yds away opposite the Sonoma Mission Inn.)
Directions from Sonoma Town SquareCome in on Highway 12 (aka Broadway) to the Town Square. At the stop sign go north (left) on Highway 12/West Napa Street. After approximately 2 miles, veer right at Bonanza Ford dealership continuing on Hwy 12. Go north another 2 miles or so. Look for Thailand Restaurant on left, turn left at 18340 Sonoma Hwy into parking lot just after Thailand Restaurant. Go to rear entrance of single story cream building. If you pass the Sonoma Mission Inn you've gone 300 yds too far.

For other maps see also Mapquest or Google:

http://maps.yahoo.com/maps_result?ed=Tw4wbep_0TpTXznZ9iUizBz9aX16R1IA7A--&csz= Sonoma++CA++95476&country=us&new=1&name=&qty

http://maps.google.com/maps?q=18340+Sonoma+Highway++95476&hl=en