I would take Hwy 101 all the way. Even the stretch through San Francisco is not too bad if you hit there after 9:30 AM or before 3:00 PM on a weekday. I would avoid this area on a weekend.
This is not all that difficult to do in a single day. If you want to it would be possible to stay at an RV park in Prunedale or two parks that are just south of Gilroy (one is the Betabel RV park) or at Moss Landing right by the ocean with a 10 mile detour). The easiest stopping point would be the Betabel but the nicest would be the RV park in the tiny town of Moss Landing where the RV park is yards away from the beach, the harbor, several excellent restaurants, and a very nice produce market.