I have helped Bob,the ironmandualsport guy, pre ride and lay out some of his rides,the Circumnavigator is a good one for sure.
Just for variety there is some great riding on the west side of the valley,over towards Elk Creek and up road 313 or Hull road,one and the same,many designated jeep trails and the main fireroad is a flattrackers dream. Its about 50 miles across the valley to get to the start of the dirt riding. Trucking bikes over isnt out of the question for more serious dirt dual sports,there is generally gas at Elk Creek. I used to trailride over there alot but not sure of where the trails are nowadays.
I would be up for a ride over that way sometime.
Some buddys and I are off to the flattrack races in Calistoga next weekend.
Should be good! Im riding the DR with the street wheels on it.