GREY'S ANATOMY - "Dream a Little Dream of Me" - On the two-hour season premiere of "Grey's Anatomy," Meredith and Derek learn that "happily ever after" isn't easy, a military doctor who brings in a trauma patient catches Cristina's eye, and the Chief and his staff reel at the news that Seattle Grace is no longer nationally ranked as a top-tier teaching hospital, on "Grey's Anatomy," THURSDAY, SEPTEMBER 25 (9:00-11:00 p.m., ET) on the ABC Television Network. (ABC/SCOTT GARFIELD) BERNADETTE PETERS