During the winter months, the South Rim Drive is not plowed, turning the road into a ski trail. The drive is 6 miles (one way), and allows access to the overlooks. Park your car at the South Rim Visitor Center, located at Gunnison Point.
For snowshoeing, try the upper part of the Oak Flat Loop and Rim Rock Trail are great treks. You will get great views of the snowy canyon...