My mother took a train, alone with a 3 yo from CA to NY without any rooming arrangements. She just landed at the train station with a suitcase and a toddler, followed the signs, and stood in an endless line to receive a room, which we indeed did receive.
I to this day can't believe she did that. She was basically quite fearful of everything. I don't remember the convention but do remember a little about the hotel. I was just together with my older brother and sister last month and they were teenagers during the convention. They got to go by themselves with their mates to the convention, again, from CA to NY.
A different time.