I cannot tell the layout of the room, but I would consider continuing the orang on the closet wall to an adjoining wall. Especially if you can paint the wall the head of the bed is on.

The orange paint color seems to be a good one I would take it around to the next wall. The baseboards should stay the white color. Don’t paint them the same as the wall color.

You could consider a stripe or two http://houzz.com/photos/22105

I go with your son's idea, an orange accent wall will transform his room and make it look bigger!

Use it on the wall with the window.

Thanks everyone for weighing in. I like the idea of taking the orange around to the adjoining wall, but that is the window wall, which is neither of the walls the bed is against. One of those walls is the largest in room (too much orange), and the other wall the bed is against (lengthwise) is the one you face from doorway. Painting this wall would create the most impact, IMO, but might also make the room look smaller I fear. I think I'll try this out and go from there. Thanks again!