In a large bowl, beat the cream cheese, sour cream, sugar and vanilla until they're blended. Editor’s Tip: You can whisk the dressing by hand, but a hand mixer will ensure that the mixture is smooth and lump-free.
Add the grapes, and toss them in the dressing to coat. Transfer the salad to a serving bowl. Cover it, and refrigerate until you're ready to serve.
Sprinkle the grape salad with brown sugar and pecans just before serving.
