We took L.A. City Tours in September and really enjoyed it. It was about $70 each for a 5 1/2 tour - starts in Marina del Rey and stops at Venice Beach - drive through Santa Monica - downtown - Hollywoods Hills to see the sign - Chinese Theater and the Walk of Stars - Lunch on your own at The Farmers Market - Sunset Strip - Rodeo Drive (stop) and then the last hour goes by homes in Beverly Hills and Bellair. There was a lot of traffic due to a triathalon, so we may have skipped Chinatown to make up time - not sure.
Also, if you have a car, go to the Getty Museum and plan to have lunch up there - it is unbelievable!