It is something to see!
Even my little children (who would have rather gone to Disney than The Grand Canyon) were impressed.
We got there early in the morning and it was fogged over. We went and had some breakfast. We cam back and the fog was halfway gone- that alone was an amazing sight. Seeing a river of clouds following the valley below you.
An hour later all the fog had cleared and we spent hours just looking at it.
My Dad loved the sights of America, and for our summer vacations we would pile in the station wagon (all 8 of us!) and tent camp across the U.S. for 2 or 3 weeks, or whatever time off he could afford. The Grand Canyon is still one of my favorite vistas, but I was a teenager the last time I was there. Flying over it is impressive, too, but nothing beats being there on the rim.