I use Trip Advisor for a lot of tips, but here are a few
San Gabriel has the Mission of San Gabriel
Old Pasadena is the downtown historic business district of Pasadena,lots of classic architecture, etc, the 50-60s California of Beach Boys songs all along Colorado Blvd
Pasadena Ca has a classic car show on March 7
The Getty Center in Venice Beach has unique architecture and the Getty Museum, including photography exhibits.
Griffith Park and the observatory.
Huntington Beach is probably where's you'd want to catch the sunset, and there may be classic cars cruising along the waterfront.
You could also go up to Long Beach and check out the Queen Mary, have lunch or dinner in the Churchill room, great food and great view of the harbor.
