Thanks to what you guys have said, I have now eliminated Reno as my departure city as I don't want to miss the Sierra Nevada and the Donner Pass view.
Now I have to figure out my best departure city from California that is easily accessible from a Vegas flight.
NO NO NO
Fly to Sacramento!
The Yolo Bus 42A runs nonstop on the I-5 from Sacramento Airport direct to the Amtrak station in downtown Sacramento. It's the first stop after the bus gets off the freeway. The bus runs once an hour, leaving the airport at 22 past the hour. So try and time a Southwest flight from Vegas to Sacramento to give you enough time to catch the bus and get to the station, where the CZ will probably be on time.
You don't miss much on the CZ between Emeryville and Sacramento, just a bit of a nice view of San Pablo Bay (part of the San Francisco Bay area) and some views of Sacramento Delta farmland.
Umm, last time I looked, Sacramento was indeed in California. Kinda makes sense, being the state capital and all. So what is the NO, NO, NO about?
The fact that the bus only runs hourly was one of the problems I had with Sacramento, and chose to take a cab.
I, too think Sacramento is probably the best bet. Pretty reasonable amount of service LAS-SMF, so getting a morning flight is entirely practical. The second best is to cut Vegas short, fly to the Bay Area the day before, and stay overnight in Emeryville at the Woodfin, which is right across a pedestrian overpass from the station.