When you contextualize it, the geological process are awe-inspiring, but the end result is, as nature goes, a solid "nice". That's it. It doesn't take a "joke" from the mom to produce that reaction.
GC can be pretty cool, but I’d not put it in my top 10 parks. Mainly because of the people and the mares ruin the effect on a hike. And, staying at the top is a bit boring.
For my money, Zion or Yosemite are better. Both with their own set of people related problems.
Off topic, but was at Bryce a couple days ago and some guy was FaceTiming at 7:30am filling the entire canyon with his and the other people’s voices. Terrible manners! Ruined the first 30m of the hike.
The thing is, it takes a certain reference point to appreciate. A more mature one.
For kids, and the younger they are, much of their daily lives of filled with continual new and overwhelming experiences. Every experience is new or very fresh. Experiences like "I've never been this cold before", or "The sun is too hot" are just as overwhelming as "That is a very deep crack in the ground", but discomfort is also more immediate, and they haven't learned to attenuate and ignore discomfort signals like adults have.
Likewise, they have less grasp of time. When you are six, or ten, a decade is your whole life or more, and waiting an hour seems like forever, while for you and me, it is a blink in the day. 100 years for kids is nigh unimaginable, and an appreciation for the untold years it took to erode the grand canyon is unavailable, mentally.
So a visit to something like the grand canyon can be less than impressive.
It does make me wonder what a thousand year old being would appreciate, that I would find uninteresting or unimaginable.
The next morning it looked great, but I knew we had experienced it in a much better way.
I saw it again a decade later, and got an overnight permit to hike and camp at the Indian Garden campground.
I have never seen anything more awe-inspiring than the view from Plateau Point. I cannot do it justice with words.
I cannot recommend that hike and view enough.