GREY'S ANATOMY - "Didn't We Almost Have It All" - Cristina and Burke's wedding day arrives - along with the interns' first exam results - and a successor to the Chief is named, as Callie and George make a big decision about their relationship, on the Season Finale of "Grey's Anatomy," THURSDAY, MAY 17 (9:00-10:07 p.m., ET) on the ABC Television Network. (ABC/SCOTT GARFIELD) ELLEN POMPEO, KATHERINE HEIGL