Combine 1/4 cup salad dressing, 2 teaspoons olive oil, 1/2 teaspoon salt, fennel bulb, and next 4 ingredients in a large bowl, tossing to coat. Spread vegetable mixture evenly in a roasting pan coated with cooking spray. Roast at 450° for 45 minutes or until vegetables are tender, stirring occasionally. Set aside.
Place salad greens in a large bowl. Add remaining 1/4 cup salad dressing, 1 1/2 teaspoons olive oil, 1/4 teaspoon salt, and balsamic vinegar; toss well. Add roasted vegetable mixture, tossing gently.