Timing is key. You should plan on staying overnight so that you can get both sunrise and sunset colors of the spectacular spectrum. The canyon rocks change colors and the best time to capture the brightest shades is when the sun is not directly overhead.
This doesn't mean to avoid taking photos between dawn and dusk, use this time to go on one of the trails and explore the flora and fauna of the canyon. Take pictures of unusual plants and trees and perhaps search for close-ups of insects and lizards.
See how creative you can get with unusual angles, even if it means getting your pants a little dirty.
Fondest memory: When photographing canyon formations try to get as much depth as possible. The closest rocks will appear brighter than those in the distant background. This will be most evident in the early morning pictures.
On cloudy days try not to get too much sky in your panorama photos of the canyon. Maximize the canyon background so that the visible horizon is near the top of your photo.
Use natural cropping with upright stone formations and old trees. This frames the photo with contrast and helps add that third dimension.
You can never take too many pictures of the Grand Canyon, so if you've been putting off that investment in a digital camera then get it before you go there.
Favorite thing: As stunning and attractive as the Grand Canyon is--it also can be monotonous to photograph (and worse yet, looking at the photos upon development.) All of the formations and colors begin to look alike after a few shots. Therefore, I would suggest trying to frame photos with some vegetation, use any clouds to your advatage for contrast and framing and it doesn't hurt to put a human being in some of the shots.
The Grand Canyon is an anomaly among national parks. For instance, 4 solid hours are required to drive from the earliest viewpoints on the South Rim to the earliest viewpoints on the North Rim. Crowding shuts out the simplest conveniences. Four million visitors a year vie for 1,600 parking spaces -- get there early in the morning and hope for the best. There is wildlife here such as mule deer and cougar which the average person is not likely to see. Daytime viewing of the Canyon can reach its peak of satisfaction in the first five minutes of your visit. Everything has to be done in advance: burros, intra-Canyon camping, and some floating. For those disinterested in desert training or hiking, the only viable pursuit here is to search out either rim under good lighting to augment a lackluster photo album. Sunrise and sunset are said to be great times for viewing, but seeing a desert-type setting is generally best only during these brief windows, where lighting conditions are most favorable.
Fondest memory: If you are to enjoy the Grand Canyon, you might spend a lot of time listening to people or reading guidebooks that mention something other than just witnessing it from either rim.
Favorite thing: Even when the sunlight is bold and blistering, or perhaps because of it, the Grand Canyon returns a rusty series of towering monuments and eroded canyon walls to the spectator throughout the south rim. Under the brightest days, the view is arguably flat and disenchanting.