Can someone tell me about the route from Hollister (25?) down to King City and then Nacimento Rd to Paso Robles? It looks like all of this route is pretty desolate (OK, California will NEVER be Wyoming) and with very light traffic.
Bruce Gordon Ti Rock N Road , Fat Chance Mountain Tandem 
It has been quite a while since I rode the route but it was a fun day ride. Thanks to the July heat there was a strong North to South tailwind that pushed us to the limits of our road gearing. The near century ride distance from Hollister to Paso Robles took four hours via Hwy 25/ Peach Tree Road then Indian Valley Road and then River Road. Auto traffic was rare. Water sources limited.
The road surface varied considerably with some rough spots and a few short gravel patches. Winter rain damage is repaired when county budgets allow I imagine so local inquiry for current conditions is advisable.
The area feels remote but is not really far away from services.
What do you want to know? I drove some of this last night. Hwy 25 is hilly and beautiful, and in very good condition, and has very little traffic. There is a campground at Pinnacles NM, don't know if they are open in winter, but there is always water in the park. I didn't know Nacimiento Road went to Paso Robles. I rode it from the big sur coast (small store just north of intersection w/hwy 1, with motel, and campground just south of intersection, with hiker/biker site, no store) to King City last spring, it is a huge hill, no traffic, gorgeous.
Any of the routes described should be great. I think if you opt to stay east of 101, you'll have a flatter ride. There are a few places to pick up water besides Pinnacles. Early in the ride, stores in Tres Pinos and Paicines. Bitterwater Tully School, just south of the King City turnoff, has water. There are some houses close to the road, and if anybody's around, I'd ask for some. Shouldn't be a problem. Once you get close to San Miguel, you'll be back in civilization for the duration.