I would say look at some of The Bakersfield Project videos I did a few months back, and start with something small. Run8 is basically an open sand box and can be whatever you want it to to a certain limit.
From my perspective the thing with California as much as I miss running it, this and other railroads take people to run. As mentioned Florida does have an RTS 24/7 server, and there are other servers available for California out there as well. I chose Selkirk for my latest efforts due to reduced size, an operating hump, and a bit more simplicity that one person can handle. However even I'm limited as to being able to run most industries (unless I want to simply run non-prototypical extended time lines).
AI is great for getting stuff moving, but ultimately it takes people to switch and build trains. When we last were running on a server for CA it would take 2 dispatchers to comfortably manage all the trains the prototype would see. We would run the clock when we had those dispatchers then paused it and ran all the locals to try and catch up. I believe to keep up with that level it would require at least 12 people on a regular basis mainly running DS, switching and yards, not counting mainlines (who could be run by AI).
So what you're seeing me do in Selkirk right now, is between runs setting up all new tagged trains to feed the hump and autorack facility. I can then dispatch, operate the hump, and shortly I'll be able to build trains.
I'm not sure what routes you also have or the version (I take it that would be 2). As mentioned no RTS software for V2 so your relying on the industry and train generation in the game. If your just looking to see traffic you can easily set an amount that is comfortable to run say on Mojave and Needles (I think that is what is included in V2). Train will generate at what ever intervals you determine but you'll find the random generation after running a while can turn into patterns. The industry themselves work just fine and will cycle after a certain amount of time, retag, etc.
All I do is avoid using the built in tag generation and create my own sets through the spreadsheet package. If your not comfortable with that you can also find either RTS V1 (though it's not user friendly will generate random waybills). There are also some more user firendly model railroad programs that can give you a basis for waybills that can be used as well.
But again it all depends on what you want the most. If your looking for something that will have activities or trains all set up for you, you won't find it in Run8. In fact any other simulator requires activity creators so once you've downloaded all the content and activities your done. The RTS concepts and software has always been about a continuous car forwarding system.
One last thing, and that is you can go freelance or protolance instead of prototype. It takes imaginiation but it can easily be done. If your looking to switch you can set up short lines and have mainline trains spawn AI and feed the yards etc. This is where the simplified local generator in V2 works well. I don't like it in more realistic applications because cars come from all over the place. But having it come from one source, works well. Florida is also another good example of where it can work because Florida gets all it's cars from 1 supply train. But again it depends on what you value the most, and what you want to put into it.
As for my videos I don't create the compact 15 minute videos because it takes time to edit things. Perhaps I'll do a live stream for 1 hour at 10pm because I'm getting a bit bored. This might be easier than typing out some of these ideas further.