I'm sure a pro will chime in with great advice, but I will say that I let my kids choose wall color when they were young, and one son chose a blue-green not that different from yours, at least as it shows on my screen. Kind of felt like you were inside a swimming pool. And it too was a large room. I found using navy accessories (drapes, comforter, etc) helped tone it down. Also hunter green, as his furniture was light oak and hunter green. And some large posters will also help hide some of the brightness, also maybe tall bookcases, if you are that set against painting and want a little less of the color to show.

Not sure how old your boys are, but I would ask for their input if they are old enough, so you can incorporate what they love. Personally I feel kids' rooms should reflect their wants, even if doesn't fit the aesthetic you are going for in the public areas of the home.

Navy blue. http://www.belk.com/AST/Main/Belk_Primary/PRD~9200287KNOTS9487J6/Nautica+Knots+Bay+Bedding+Collection.jsp?navPath=BedBath/Shop/Bed/BeddingCollections/Casual&ZZ%3C%3EtP=4294923165&ZZ_PO=100&fO=Category_Path%3A%2FBelk_Primary%2FBedBath%2FBed&ZZ_OPT=Y&PRODUCT%3C%3Eprd_id=845524442232997&FOLDER%3C%3Efolder_id=2534374302215854&bmUID=lowI1BZ&changeViewInd=y

Navy and a medium/dark gray. Touches of white.

@torreykm - LOVE that one!!!

Thoughts on this one: http://www.target.com/p/maverick-comforter-set/-/A-16740596

http://www.garnethill.com/pirate-27s-life-percale-bedding/bedding-home/duvet-comforter-covers/414315?&defattribvalue=

http://www.garnethill.com/rockets-quilt-and-sham/bedding-home/quilts-coverlets-shams/395455?&defattribvalue=main

I like the maverick from Target, though the walls seem to lean more green than the aqua. It still might work though.

@Torreykm, yah, I can see that... I love the ones you shared!

Go dark.

That green is an in-your-face color that needs lots of contrast.

Why not repaint? I repaint my kids rooms as decor needs change. It is the cheapest, simplest fix to any room, imo. My older kids painted their own rooms when we moved a couple years ago. It isn't the world's best paint job since they were 13 and 11 at the time, but they learned how to paint a wall! :)

In staying true to not wanting to paint, I think you could pull off a beach vibe for your boys - the sisal-colored pillows in the picture are a beginning - use blues and greens - watery colors and sandy tones. Decorate with some oars, some beach posters.

Given you don't want to repaint the entire room, maybe you are open to painting the upper half the same as the bottom (more masculine and richer) and include the chair rail, which will all make the room feel less choppy. Bedding is easy once you decide on the color you want to accessorize with. Giving them reversible comforters is a great idea, so each one feels more unique.