During this trip, we hiked the Rim-to-Rim-to-Rim route over two days. From South to North, the 21 mile trail drops about 4860 feet from the South Kaibab trailhead to the Colorado River and then climbs about 5840 feet to the North Kaibab trailhead on the North Rim. We hiked for 13 hours the first day going from the South to the North, camped at the North Rim after sunset, and then hiked 11.5 hours the next day to get back to the South Rim. We managed to catch a spectacular sunrise at Ooh-Aah point on the South Kaibab trail, but unfortunately missed the sunset on the way up to the North Rim. During our night at the North Rim, the temperature dropped to 12 F according to the thermometer we had with us. As a result, we stayed in our tents past sunrise (which is when we wanted to start hiking back) to let the air warm up a bit before breaking camp. The spigots at the established campsites were turned off a few weeks earlier and so I had to haul about 7.5 liters of water from the river next to Cottonwood camp up to the North Rim. Together with my photographic equipment and water, my pack weighed about 45 lbs or so.
This hike is quite special, especially since the South Kaibab trail follows a "ridge" line down to the river; The views are outstanding and change as you move from the South to the North. My only gripe about the hike is that the trail is shared with mules and hence there's plenty of mule poop and pee all over the trail. Apparently, quite a few people hike down to the canyon bottom, stay at Phantom Ranch, and then take the mules up. The mules are used to supply Phantom Ranch and to ferry these people up on the return trip. In any case, the development at the bottom of the canyon is an eyesore.

After hiking the South Kaibab trail and catching the sunrise, we were a little let down by the overlooks on the West side of the South Rim because it was quite similar to what we'd already seen in the past couple of days, only in worse light. On hindsight, I would give the overlooks along the Hermit Road a pass and head straight to the Eastern overlooks, which offer a different view of the Grand Canyon. I thoroughly enjoyed the sunset at Lipan Point and Desert View overlooks.

These photos aren't great but they show the route that we took during the hike.