I have taken the auto train a few times. In 2007, the summer promotion was kids ride free, but the past couple of years it has been kids ride for $19 each way. I believe the promotions are normally announced in April. I have typically booked earlier than that and then when the promotion did come out, I would check to see if it saved us money. (You can cancel your reservations without any penalty if the actual tickets have not been issued) I was able to make new reservations which saved us a little twice. Last year, though, I wasn't able to book the promotion for our dates, so I kept my previously made reservations. The cost for the auto train increases as you get closer to the date of travel, so it makes sense to book it as soon as you can.