I see you're from the "Bay Area". Either the Weeks Pit or the Top Gun pit is close. Keep in mind the pits are the only place you can spectate. If you want to get involved there are always help needed at Rawhide pit.
I would suggest "Rawhide" as a start point. Surrounding area the Bike's and Vehicles are at race speed with in a short drive from the pit. Also the ALT 95 road crossing South of Weeks..
Lots of people camp out on the final summit run into Dayton.