Hi Miss Kayla!
Well first off I love your name because that is my 4 y/o daughter's name as well.
Second in trying to answer your question I would say these are all some of the nicer parts of Southern and Central Cal. The big piece of advice you will get on here is to make sure you have a job lined up. But it sounds like you may already have that covered for now at least.
Coastal CA is a great place for young ppl and many flock here because of it. Most ppl your age are living the college lifestyle attending UC Santa Barbara, Cal Poly SLO, etc... The thing with CA is there is a lot of opportunity 'but' it takes a lot of hard work to get somehwere.
If you come out here my main advice to you is to life by the motto 'work hard and play hard.' Life is faster paced than what you are used to in Montana. But you are young enough to handle it if you so desire. Your best bet IMO is to continue your education to get a decent paying job. The cost of living is higher here. And while some ppl just scrape by from paycheck to paycheck it is good to work toward bettering yourself long term.
Anyway my second biggest piece of advice is to come out and visit. See what you like/dislike about these areas. Then pick the one you like the most. Look at it as an adventure, a stop along the way which could lead into something more.
Oh and roomates are essential if you are on a tight budget!
Enjoy,
Derek