I took a long Amtrak train trip from Atlanta to Baltimore with my 9-year-old daughter this summer. As far as I could tell, there was no way to reserve specific seats in coach on our particular train ahead of time. But we arrived as early as we could and, to our delight, were treated to a near empty train. We sat together in a two-person row and had a really nice trip up to Baltimore.
On the way back? We boarded at Union Station and the train, having arrived from New York, was already packed. The conductor told me he would try his best to seat us together but couldn’t guarantee it. You should have seen the terror in my daughter’s eyes. It would be a 14-hour overnight train ride. Sitting her next to some stranger that whole time? Absolutely not. No way.
https://www.upworthy.com/entitled-parent-discovers-airline-has-moved-their-toddlers-seat-just-ex1