Place chicken in large resealable food storage plastic bag or glass baking dish. Pour 1/2 cup salad dressing over chicken; seal bag or cover dish. Refrigerate 8 hours or overnight to marinate, turning once or twice.
Heat oven to 400°F. Remove chicken from marinade; discard marinade. Arrange chicken at one end in ungreased 15x10x1-inch baking pan. Place potatoes, onion and corn at other end in pan.
Bake at 400°F. for 20 minutes. Add zucchini and bell pepper. Sprinkle vegetables with salt and pepper. Bake an additional 30 to 40 minutes or until chicken is fork-tender and juices run clear, stirring vegetables once during baking time. Before serving, drizzle chicken and vegetables with 3 tablespoons dressing.