As detailed on the directions page, Lake Arrowhead is about two hours east of LAX, Burbank and John Wayne (Orange County) airports, and about an hour east of Ontario airport.
CARPOOLING & CAR RENTALS
Our transportation recommendation is to rent cars and carpool. Rental cars in the LA area are relatively inexpensive, and the trip is not an unpleasant one -- especially the second hour, which winds through some really lovely mountains. The venue has limited parking, so they (and we) do ask that you try to carpool and fill your car. Closer to the Con, there will be plenty of folks arranging carpools in the forum. It's a great way to make a few new friends on your way to the event.
A couple of basic guidelines: if you're a passenger in someone else's car, it would be great if you could offer the driver about $20 each way to defray rental and gas costs. Also, if you're a driver, make sure to get the flight and contact information for your guests, in case of delays. We don't want anyone getting left at the airport.