The Boston Celtics won their first NBA title in 22 years, so where are they going to celebrate? No, not Disney World. Kevin Garnett and Ray Allen are heading to New York to sit down with David Letterman on Wednesday's Late Show (June 18, 11:35 pm/ET, CBS).The Celtics wrapped things up in Game 6 on Tuesday night with a 131-92 victory at the TD Banknorth Garden, the largest margin of victory ever in an NBA Finals series clinching game.UPDATE: Ratings are in, and the game scored 16.88 million viewers, the most watched Game 6 since 2000. Led by Sunday's Game 5 (17.39 million), the 2008 Finals make up the six most-watched programs in June (to date), averaging 15 million viewers. That's a 61 percent jump from last year's dead-boring Spurs rout of the Cavaliers.