Man, I wish I could get my wife to join me on an overnight. But standby travel... not her thing.

There are a few of our overnights where transportation is by a car that will fit only 3 crew. On those, I'd uber.

I would never try this with JUST a child too young to spend the night on their own at an airport/hotel. Flights get overbooked, airplanes get broken, and flight crews time out. Now if my wife was traveling with the kid(s) on said occasion, that's another story.