A few helpful links:
The Grand Canyon is an all time favorite that needs no introduction.
If you're down for a little road trip, Sedona with its gorgeous red cliffs and canyons, or Scottsdale with its old-town charm (or both!) might be exactly what you're looking for.
For the hikers among you, a day's hike around Camelback Mountain, Superstition Mountain or Papago Park might be just the workout you need after gorging on all the wedding delicacies.
Downtown Phoenix has the best of food and nightlife.
The Desert Botanical Garden or Phoenix Zoo are one way to take in the unique beauty of the region with a little less exertion.