Dunno if you are familiar with all of the roads, but Google Maps routed through Highway 12 south of Napa if going to Santa Rosa. Either 128 from Winters (west of Davis) or Wooden Valley Rd to 121 (Monticello Rd) from Fairfield is far better for cycling with not much change in mileage (Stateline to Plymouth to Bodega Bay ~= 250 miles).
If you are starting on the north end of the lake, following I-80 wouldn't be a problem and would keep the mileage ~250 -- you need to ride the interstate for a couple miles, but it is bike legal, extremely wide, and goes by fast. In that case I'd stick to following the course of I-80 down to Roseville ... don't go across to Grass Valley and Yuba City which lead to endless farmland.
Last edited by anotherbrian; 11-07-20 at 11:51 AM.