your best option is to drive. you can do it in 5 hours if you time your departure correctly to avoid traffic and you don't drive like a sissy. you're looking at 1 to 1.5 tanks of gas for the trip - much cheaper than flying, and it takes no more time once you count getting to and from airports at both sides, going through security, waiting around for your flight, etc, etc. a newspaper did a little race BEFORE 9/11 and the car won by a fair margin. with modern security at the airport, the car would win by an even greater margin.
edit: IIRC, Amtrak does NOT run direct to the LA area. you ride to like bakersfield, then get a freaking bus. great idea if you want to spend 48 hours getting there and ride along with all the drug addicts and weirdos.