"I’m drawn to places that beguile and inspire, sedate and stir, places where, for a few blissful moments I loosen my death grip on life, and can breathe again. It turns out these destinations have a name: thin places." (NYTimes, Eric Weiner)
The term "thin places" is Celtic in origin, the gist of it's meaning is a place where heaven and earth are very close together. I interpret that as a place that takes your breath away, startling consciousness into an orientation beyond the mundane. The physical locations of thin places may be unpredictable and different for each person since they are really more about the person than the place, but here in the rarified air above the abyss you might just find yourself attuned to such a thinness.
The walking trail along the South Rim provides breathtaking views at every turn. The geology interpretive center at Yavapai Point is also a favorite. Sunrise is around 5ish and it's worth getting up to greet the day. There will be more resident critters and less humanity encountered besides the lovely air temp. and magical light show as dawn pours into the canyon.