Rinse and dry grapes thoroughly. Set aside.
In a large bowl, beat together cream cheese, sour cream, granulated sugar, and vanilla extract until smooth and creamy.
Fold grapes into the cream mixture and stir until evenly coated.
Cover and refrigerate for at least 1 hour before serving.
Just before serving, sprinkle with brown sugar and chopped pecans for a sweet, crunchy topping.