Someone asked the same question awhile back (maybe a year ago or so?) and there were a number of answers, so you might try searching the forum archives for it. My contribution to it:
If you're there when it's clear and not too smoggy, try driving up Mt. Wilson (in the high mountains at the north end of the LA basin) at night. The view of lights extending for miles and miles across the basin is stunning, and would make some interesting "city light" style photography.
Lisa