And one more idea. There was a gravity railway north of San Francisco on Mt. Tamalpais. Look at this picture! http://www.alamedainfo.com/Mt_Tamaplais_CA_PC_04.jpg
This could be a really fun ride if highly immersive as well as being a major "people eater" judging by the capacity.
The ride could use the Expedition Everest idea by first being pulled uphill by a train like in this image http://www.alamedainfo.com/Mt_Tamaplais_CA_PC_09.jpg
and then at the top section an earthquake shakes the cars causing them to decouple from the engine and the journey downhill, backwards begins.
Then stopping inside a mine tunnel some miners could yell to get out as they have just set off a fuse to a stack of dynamite. As the explosions begin you begin moving forward again.
It's a bit of a clone from EE but it could be fun and still a California theme.
Best of all, place it at the Route 66 area and help hide the outside world and extend the mountain range.