If you are going to be near the coast such as Newport Beach, Huntington Beach, there is a long bike trail that runs along the coast that goes south. Check out these links for some good info on the HB trail as well as others in the bottom. http://www.nearfield.com/~dan/sports/bike/beach/hunt/
http://www.biketrails.com/ocbhbss.html


Good luck, have fun and let us know what you decide.