Shot with Nikon D7000, Nikkor 16-85 and Nikkor 70-300 f3.5-f5, March 2011.
Shot with Pentax K-5 IIs and Pentax 17-70 f4, November 2012.
My visit to the Grand Canyon was at the end of March, 2011 for two days. I flew into Flagstaff airport which gives a fairly easy drive (a little under two hours) to the Grand Canyon village on the south rim, arriving in time for sunset on the first evening. I stayed at Maswik Lodge in the park itself. It is walking distance to the rim, but you will likely want to drive out to other viewpoints for much of your shooting. The nearby views are good, but a long way short of the best the Grand Canyon has to offer. There is also a good range of accommodation just outside the south entrance to the park in Tusayan.
There are two routes along the rim from the grand canyon village. You can drive out on the Desert view road, but you have to take the free shuttle bus on the hermit road. Check with the park newspaper, but the shuttle service was operating before sunrise and after sunset when I was there. The service runs about every ten minutes. There a fair number of other visitors during my visit, but there was enough space to to find plenty of great unimpeded views. In the park there are limited options for dining, I recommend getting reservations or eating early if you don’t want a long wait. There are many viewpoints in the park and three days wasn’t nearly long enough for all the photographic opportunities.
The Grand Canyon is generally aligned on an east-west axis, so most viewpoints will provide good sunrise and sunset shooting. Mather Point is the first viewpoint you encounter once you reach the village and it is likely the most visited and a frequent stop for tour buses. The views are spectacular, but very well known. I had very good end of day light at this location.

View from Mather Point, evening light
I didn’t find the views at Yavapai Point to be quite as expansive as Mather. I visited for sunrise, but it appeared to be more of a sunset location. There were a couple of rows seats, all empty, overlooking a shady area of the canyon. I imagine the seats would be full when the sun has moved around later in the day. The other areas around the viewpoint were crowded on the morning I was there and you will need to arrive early to grab one of the few prime sunrise spots. I ended up walking along the rim and found a nice view of the Battleship mesa lit up in the morning sun.

Battleship Mesa, early morning light
I had my best shooting out on the Desert View road at Moran point and Lipan point. These viewpoints are further out from the village and consequently fewer visitors. I tried Lipan on my first sunrise shoot, but unfortunately the wind was gusting up to 40 m.p.h. - not very conducive for slow shutter speeds. I drove back to Moran point, it was still windy, but not as bad as Lipan. Moran point has some stunted trees that can provide some nice foreground interest. I went back to Lipan the next morning when the winds had dropped off some. In addition to the various side canyons, Lipan will also give you a good view of the Colorado river. Very good light at both locations, including strong pink light from the sunrise on the second day and some good patterns of light and shade from the passing clouds. The drive out to Lipan point is around 45 minutes from the village.
Desert View is the furthest viewpoint. It was fairly empty when I was there, but I am guessing from the size of the parking lot and the presence of a gift shop, this viewpoint can get crowded in the summer months. There some good expansive views here, but access is limited to the viewing area. It is also the closest viewpoint to the east entrance of the park. There are many other viewpoints along the Desert View road and worth a stop if the light looks interesting. Ironically, I found the Grand View overlook to be one of the least spectacular view points!

Desert View, morning light
I did try the Hermit road shuttle bus, but the weather was not cooperative and I had mainly cloudy conditions with fairly flat light. However, the views were spectacular and assuming a return visit I will likely try for some sunrise and sunset shooting on this road. Hopi and Mohave points looked very promising.