Preheat oven to 400°F. Stir peaches, berries and 1/2 cup sugar in large bowl to blend. Let stand 15 minutes.
Meanwhile, stir flour, oats, milk, vanilla and remaining 1/2 cup sugar in medium bowl until blended. Mix in butter (batter will be thick). Spread batter in bottom of 8 x 8 x 2-inch glass baking dish.
Spoon fruit mixture atop batter. Bake crisp until fruit mixture is cooked through and bottom crust is brown, about 45 minutes. Let stand 10 minutes. Serve crisp warm or at room temperature with ice cream.
