My daughter is 9 and while I've let my daughter watch the train scene of Stand By Me I don't think I'd let her see all of it just yet. That's because the Trestle is in Northern CA (Lake Britton near Burney Falls) where I grew up. When the movie came out I asked my parents about it and they said, "Oh yeah" and proceeded to tell me all about it. Apparently one of their friends rented out their house for the indoor scenes and complained about the inconvenience....Especially after the movie came out and they didn't use any of the footage from their house LOL. The tracks have been torn off the trestle now but it's sure fun to see it in the movie.
Other than that bit of trivia, I agree with Christy Lee. You also know your children, some are more sensitive to this sort of subject matter than others. The rest of the film, aside from foul language is classic growing up in yesteryear. We actually did follow the road that runs alongside the tracks out to the falls on our bikes, sometimes without adults with us. A lost era and experience for kids as there are few if any places where kids have that kind of freedom.
Another movie that might be good is The Sandlot if you're looking for childhood/friend/bonding sort of movies. If I remember correctly, it's tamer but has much of the same kind of fun. I remember a dog in a neighbors yard where the baseball ALWAYS goes. Mean dog, grouchy neighbor, lost ball...until someone is dared, loses a bet and has to retrieve the ball.