I'll be visiting Los Angeles this Friday through Tuesday with my lady. I'm wondering what to do while I'm there(besides sitting in traffic)... What are the must do's?

I plan to go to the beach, I hear Venice beach is sketchy so I was thinking Malibu or Santa Monica. Also was going to do hiking at Runyon, but if there's anywhere better let me know.

Can you guys recommend some good museums, restaurants, shopping, nightlife etc?