Take a coach trip to Universal, or drive if you know the way & think you could do it safely. Other theme parks such as Disneyland. Go to Venice beach & watch the cool dudes strut their stuff but be careful, the night the place can be really dodgy. As tunnsey said the amusements on Santa Monica pier & go to the beach/walk the promenade.
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http://answers.worldnomads.com/questions/united-states/4362/what-are-the-best-places-to-visit-in-ca-for-a-6day-vacation about 9 years ago