If you're concerned that they won't enjoy it or will be fidgety, won't stay in their seats, etc, I'd suggest standing at the back. It's not a very visual show, just a big choir and a narrator standing at a lectern, so it's not like it's critical to have a good view - or any view, for that matter. The plaza in front of American Adventure is right opposite the stage, and you can hear the show very clearly from there, so if they want to run around a bit, or just wander, or sit at a table and have a snack, you'll still hear the show.