I'll be doing this same route in a few weeks time. Can't wait. I haven't booked a flight or train ticket yet but not having a car makes the choices more clear... i HAVE to get up to Portland by boxing/unboxing my bike. Many people recommended the train which leaves at night from Oakland and arrives around 3:30pm the next day. They say it's great but I'm not sure if I want to start the trip with a long train ride when I could get up there on a plane in 50 minutes.

But to your point, when I was a kid my family moved out to San Diego from the east coast and we had some people drive the car out, some students if memory serves me. All went well with that. I suppose if you find the right people and the needs and schedules match up it's not the worst option.