Being from So. Cal, I guess I should weigh in on this thread.
Wilson, you should have stayed put. Long Beach has plenty to see and do. Pine Ave. is walking distance from where you stayed and has more than enough restaurants, bars, clubs etc. to keep you busy. If you venture out a little, Belmont Shore will be the next logical stop....about 15 min. drive to more restaurants ,bars etc. and more good-looking women that the entire state of Virginia.
You drove to places even the locals (like myself) don't go. There is no reason to go to downtown L.A. As mentioned in a previous post, the "west" side is great....Santa Monica, Venice beach (freaks galore-but safe), any area around UCLA campus, etc.
I will agree that Downtown L.A and the area to the south is a pit. Crime is rampant, car jackings, "bloods" fighting "crips", Mexicans against the Asians, Blacks against everyone..... A white boy driving a rental car in this area is a recipe for disaster.
Seek a little advice before you travel around a strange place and I think you'll have a better time.