SERIES RETURN: This also is a series premiere of sorts, because Conan O’Brien has made significant changes to his approach to the late-night arena. Tonight’s premiere on his TBS Conan show will be 30 minutes long, not an hour. And O’Brien is ditching his suits for more casual wear, and ditching the desk. And he’s focusing on one guest per show, with tonight’s opening guest being late-night good-luck charm Tom Hanks. Good luck, Conan…