I recently redid my DS's rooms (he just went off to college). What we did was to work with a black and grey color scheme. It gave it a more sophisticated look, very masculine. For his dorm room we did more of a navy and white color scheme (his furniture there is all oak). Again with black accents (desk chair, stacking storage cubes, etc). He recently bought some posters to put up. I think a nice neutral wall works well for allowing you to personalize your room with artwork, posters, bedding, etc. The paint we used was Benjamin Moore Revere Pewter whioch I highly recommend. It looks fantastic with black furniture accents. And for his curtains, we used painter's dropcloths; very inexpensive with a coarse feel to it. You room would look nice with an area rug (perhaps a geometric print?) If you will be having friends hang out in your room and are a young man living at home (I assume), I'd also look into a mini fridge. And, as I told my own son, there is nothing more welcoming for friends (esp. of the female variety) than having a neat and tidy room that doesn't smell like a gym bag! I bought him a room deodorizor from Linens 'n Things that you just leave in a corner and it absorbs orders, yet doesn't emit a smell of it's own.

I would hang the decal on his door (back or front). Kids love photos of themselves and photos of their family. So at the foot of his bed I would hang a print (could even be a canvas wrap) of him with his family in the largest size you can afford. EDIT: make sure you hang it low, so he can see it easily! Or you could do a collage frame with shots of various extended family members. My little guy loves pointing out the people he knows in photos (he'll be three in March) and it helps little ones feel a connection with family who is far away that they might not see often, if that is a situation you can relate to. Other than that, a low pile rug that he can drive cars and build with blocks on and you're finished! It's a perfect room for a little one to grow up in: just enough room to play and small enough to tidy easily, a neutral wall colour to let his imagination do the work, a big mirror for dress-up days and making faces and generally admiring himself. Good job! Oh, and about the window, go with the code spacing for railings when determining the safety (I think it's 4"). If he can back his body out and his head gets trapped, oh no.

White could work, but maybe you could find something that incorporated that chartreuse color. Do you have any ideas or themes you’re looking towards? I was thinking about that geometrical bedding. It reminds me of a rubix cube or tangram. Maybe you could use something along those lines to decorate the walls. Off the top of my head I’m thinking either framing or gluing some tangrams together to hang. Maybe a poster print from a rubix contest. I’ve also seen framing game boards or the box covers. That could expand your color options too. Tangrams

Look for a great fabric for children for curtains and decorative pillows or to cover the rocking chair cushions and then choose a color from the fabric for the walls. Reconsider the barn siding wall; the room is small and you really don't need an "accent" wall.