The Getty Center and Getty Villa are two entirely different places and probably can't/shouldn't be done on the same day. There is no shuttle between the two and you have to travel the most congested freeway in the western hemisphere to get from one to the other. Ok you could take Sunset if you don't mind a winding canyon road but still pick one and forego the other.

Try to do Griffith Observatory and Huntington Library on the same day, it will minimize traffic time and they're relatively close to each other by LA standards.