My R65 goes to
Ted Porter's BeemerShop in Scotts Valley (near Santa Cruz). That's another 1.5 hours south of SF.
You might also look at taking your bike to Ozzie's BMW in Chico. Ozzie is an old time dealer and they know airheads.
Another thing you can do is join the NorCal Airheads. They have monthly events and there are pretty regular tech days where you can work on your bike with the help of other enthusiasts. I have one at my house every April and there are others.
A lot of dealers don't like to work on old bikes. The main reason being that they tend to have a lot of "deferred maintenance" that can quickly add up to much more than the bike is worth. A dealer doesn't want to end up with your bike instead of payment for service because it's a hassle to sell and he won't get his money back. So a lot of them say "no points bikes", for example.
Another reason why a dealer may not want to work on your bike is that they don't have a tech who is well versed on them. The old timers can beat the flat rate manual on routine service work, but newer mechanics who don't have the experience and training on these bikes will not be able to do that. When a mechanic meets or beats the flat rate manual, the dealer and the mechanic both win, but when it takes a lot more time than the manual calls for, they lose on the job. BMW still offers a factory training course for mechanics on the airhead bikes, but a two day course does not make someone an expert.