I just did 2 motorcycles and a car today and got my Calif drivers license back (moved to Nevada and back, but bought two motorcycles and sold another one while I was a resident there). My apologies to the Auburn DMV office for my earlier disparaging remarks -- they were beyond wonderful, and dramatically changed from my last visit there approx. three years ago. Friendly, efficient, and it was uncrowded -- I got there about 2 pm on a Wednesday and I hear Tuesday is good too, but that it gets more crowded later in the day and that Monday and Friday can be a bitch. The horribly obnoxious 350 lb. woman who used to snarl at everyone apparently no longer works there, and I dealt only with friendly and helpful folks.
Big props to pawtracks for the engine number heads up. On the Feejer, it's on the back of the tranny, between and above the rear motor mounts . . . AND you gotta use a mirror to read it if you don't have the rear tire off (bring the mirror and a flashlight with you to help your DMV personnel cruise through the process (VIN, odometer reading and engine no. identification). On the Blackbird, it is just above and inside the oil filler cap. Also, note that they'll charge you a penalty if you register the vehicle more than 20 days after you establish residency or begin your job in California. Other than that, the fees weren't as bad as I expected. You don't need proof of insurance to register it anymore -- the insurance company provides it directly to the DMV, as well as direct provision of any cancellation info after registration (and they suspend your registration if you can't provide proof of insurance then). I came with proof of new Calif insurance on everything, but she didn't need it. Will probably need a smog certificate on any car (but not bikes) you bring into the state for title change, too.
Lots of excellent info in this thread, and some of what I posted earlier was the result of reading a similar thread here some time ago. Gracias.