Some really excellent tips from an experienced chef — Parboil them to reduce the chance of dehydrating the outsides before the insides get done. Add orange peel and fresh rosemary. Coat thoroughly with oil. Roast aggressively at high heat, which they can handle now that they've been hydrated. Near the end, coat with a little orange juice, honey, and finely-chopped rosemary. Then roast just a little more.
Many of the same techniques can be used for other root vegetables such as sweet potatoes, yams, parsnips, rutabagas, and fennel.