I did that trip once in a car as well about 15 years ago. We camped at Big Sur along the way. It was incredible. On the bike, so far at least, I’ve only stuck around the San Diego to OC area. I’d like a slightly better road bike if I was going to go THAT far North again.
I have made a few subtle changes to my bike, I have re-padded both seats for a bit more comfort and added a bit extra to the front of the rider seat to stop me sliding forward and it works well,
fitted a fenda extender to front and rear to deflect some of the road mess,
the standard handlebars...