Bike to North Hollywood Red Line, catch the Blue Line ot Long Beach. For the commute home you can take the San Gabriel River path. Doesn't give you much in the way of hills, but the Blue Line can be rather entertaining. The Metrolink from Northridge to Downtown is faster, and you can catch up on sleep. I commute from North San Diego County to Santa Ana, bike-train-bike, and other than getting up at the butcrack of dawn, it doesn't suck.

If you gotta move, Irvine. It is the gateway to the awsome bike paradise of Sout Orange County, though the drive from there to Long Beach can suck a little.