I worked at the Grand Canyon for 5 years. Working with people from all over the world and all walks of like was such a beautiful expierence. As for the Grand Canyon, pictures do no justice to the place.
If it is your first trip to the Grand Canyon, make sure you go on a Bus Tour out to Hermits Rest, or to Dessert View. Also, go prepared with a good pair of hiking boots. DO NOT take brand new boots, bad idea. Make sure you carry water, even if you are just hiking the rim. A good hike is from Mather point back to Bright Angel Lodge. Don't forget your camera and extra film. If I ever go back I would like to hike from the North Rim to the South Rim. It's only about 26 miles.
Good Luck, and enjoy one of the most beautiful places in the world.