Whisk vinegar, mustard, citrus peels, and honey in small bowl. gradually whisk in oil. Season vinaigrette with salt and freshly ground black pepper. Preheat oven to 400°F. Toss beets and oil in large bowl; sprinkle with salt and pepper. Wrap each beet in foil. place directly on oven rack; roast until tender, 60 to 70 minutes. Open foil; cool 30 minutes. Rub skins off beets; cut each into 8 wedges. Sprinkle with salt and pepper. Place spinach in large bowl; toss with 2 tablespoons vinaigrette. Divide among plates. Add beets and citrus segments to same bowl. Add 2 tablespoons vinaigrette; toss to coat. Arrange beet mixture atop spinach; sprinkle with cheese and chives. Serve, passing any remaining vinaigrette.