One of my sons has that exact madras quilt in his room. He doesn't have any curtains, he has plantation shutters and that looks good with it. For curtains, I would do plain navy blue or plain red tie-backs. PB has some cute metal things to keep the curtains in place. My other son has them in his room and they look great!

I saw black out curtains not too long ago at Target. I'd put those under any fabric curtains you buy OR you could do a roller shade in black out material, that way it's out of the boys reach during the day and then use whatever fabric curtains fit your taste.
I'd use a solid color for the curtains as I think the pattern in the bedcoverings is more than enough pattern for one room.

I am not a fan of roller shades but they do really block the the light well if you get room darkening ones. You can get nicer "custom" ones from the big box stores. My son can't sleep if there is any light creeping in and we have a street light near by. I also have simple navy blue tab curtains over them on a nice black/wrought iron look rod.

I am not a fan of panels in a little kidâÂÂs room - too much in the way, and too much chance for them to hang on them, LOL!

I would get the blackout roller shades as suggested, that could hide up high during the day if not needed, and be out of reach of the kids with no cords involved. Maybe go to the Pottery barn Kids site and look at the twill valances in Navy, which have a bit of white piping, or whatever other color you would want to pull out of the bedding. Those would hide the top of the window with the roller shades, and bring some color up high on the wall. The color of the valance would depend on your wall color, or what you are using for the accent color in the room.

If you want more color up there, you could buy a matching madras panel and cut it up to make valances. Or, if money is not an issue, you could buy several of the pillow shams in the plaid and hang them from clip rings for valances.

The matching panels are blackout lined, if you do want panels. They also sell plain color blackout-lined panels.

My 3 1/2 year old has the same bedding and I went with a navy panel. I had to do a bit of leg work to find a "true navy" to match the piping on the edge of the quilt (pbk panels did not match, much ligher) but I did end up buying from JCP. The panels are blackout lined and look great with the bedding. One piece of advice that I can offer is if you decide to go with panels, use cliprings so that the rod is not ripped out of the wall should it get tugged on.

i have a large navy blackout roller shade in one of my son's rooms and it's been really great through the years. i topped it with a simple tab valence.
also, a simple valence for boys' rooms is to shir a fabric sleeve on a 3-5" rod...and mount these rods together to determine the thickness of the valence you want...fabric can be a single color or you could make different rods different colors--navy-red-navy on 3"rods to make a 9" valence. adds nice color and is cheap and simple to do!

Thanks for all the suggestions. I'll be sure to post when the window treatments are done. tsan231, thanks for the info about the PB navy not matching the quilt.