One hell of a road trip! Sounds like a better schedule IMO .

Another thing to note... I only saw news blurbs, but the recent rains have damaged many of the historical sites in Death Valley (but I don't remember specifics). I'd suggest that you research what's going on there so that you don't arrive to a site under construction or off-limits.

Another suggestion: When you get to SF, I would ditch the car and start taking rideshare (like Uber or Lyft... avoid the taxis), or public transportation to get around. That way, you don't have the hassle of trying to find parking (which is either a miracle if you find street parking, or expensive for private lots).

LA is more car friendly, but if you're just sticking to the beaches, you may not need a rental car there either.

I just had a stream of consciousness, so here's a list of my personal "gems" for the trip:

One quick stop I'd recommend on your route is to stop at Bishop, CA and grab some of America's best jerky at Mahogany Smoked Meats. They'll let you sample everything first... my personal favorite is the Sweet and Spicy Beef Jerky. They also have exotics like buffalo and boar jerky.

Also on your drive from Vegas to South Rim, if you see a roadside shack that sells Fry Bread, stop in for a tasty snack. It's exactly what it sounds like... fried bread dough. It ends up being like a donut, but with a more yeasty/bready flavor.

In Napa, I really enjoyed the Oxbow Public Market... great variety of things to eat, something for everyone. It's counter service so everyone picks what they want then sit at the communal tables. I especially liked C Casa (tacos) and Ritual Coffee Roasters, and have had Three Twins (ice cream) at their location down here.

More than happy to provide other suggestions if you'd like. ^