Books up to 13 months in advance for El Tovar, Bright Angel, Maswik, Kachina & Thunderbird Lodges and runs lottery-reservations for Phantom Ranch on the canyon bottom. Call the South Rim Switchboard (928-638-2631) to check availability within 48 hours.
It also books South Rim bus tours, overnight mule rides from the South Rim to Phantom Ranch and dining at El Tovar and the Arizona Room (the only South Rim restaurants that take reservations).