This is the fourth visit to this confluence.
While in the San Francisco area for business reason I decided to go confluence hunting (instead of hitting the shopping malls) and found two points quite easy to visit in one day: 38°N 122°W and 38°N 121°W.
Both confluence points are next to a road of easy access.
This one, 38°N 121°W, is in front of a house just to the side of a road (J6) that runs north to south pretty much following the W121.0000 line. To get here from 38°N 122°W all I did was follow highway 4 East past Stockton and took a left where it intersects with J6, right in Farmington. The roads are very straight, very flat and full of agricultural grounds, mostly fruits. It is a nice and entertaining journey.
Be careful not to exceed the speed limit once you get into empty roads; I saw the driver of a Jaguar that passed me at about 80mph having a conversation with a highway officer a few miles down the road.