Light grays really work well. I used this in our last house when my 2 boys shared a room. They were 6 and 4 at the time. It was an east facing room so it got tons of morning light. It's so neutral you can basically use any colors in there, although I preferred to use navy, red and kelly greens as the main accent colors. Mostly because I had space themed quilts with these colors. I don't have a color name, I mixed my own gray. I'd had a very dark gray oops paint I picked up for $5 and mixed it with white until I got a shade I could live with. Like you, the room was previously occuppied by a girl. It was a nursery and it was painted Winnie the Pooh Honey Pot Yellow. I don't know your space, but Austere and Escape read very green to me. Is that the undertone you're looking for? Personally, I tend to go for the lighter, warmer grays or barely there. I really like Agreeable Gray SW 7029. A new color for 2011 (I think) that's not in my deck is SW 0055 Light French Gray, it looks pretty online, not so sure about in person. Maybe take a look at Restoration Hardware's Pale Silver. Some of my favorite bloggers from younghouselove.com just did their family room in a very pale gray. They used BM Moonshine 2140-60 mixed in Olympic No-VOC paint. Google gray bedrooms or just rooms and there's a lot that comes up. The thing I love about SW, is they do the large sample pots vs BM's itty bitty ones (off the rack, they'll mix bigger ones). I like that even though a color doesn't work out in one room, you have enough in the nearly quart sized can to check it out in other rooms. Try painting big foam core boards with your colors. Don't forget to write the color on the back. That way you can move it around the room to see how the light affects the colors throughout the day. Also, you can re-use the boards for another room or pass them on to friends/family when they admire your awesome room! Good luck!

This sounds like a lovely space for them. I think that the teen view of decor is very different than ours and what works and what does not. This could be a nice project for them to make the choices together, and will also let you off the hook if one of them does not like it. My DD is also drawn to strong colors, esp. orange, but it is quite overwhelming on the walls. Last year I bought her a bright orange bedspread and we are updating it now and her new choice is an aqua blue. So it seems she herself is now finding her room to be "hot" and wanted to bring some coolness to it. Look In your situation, I'd really encourage the girls to agree on a wall color with one accent wall. Show them some websites and catalogs from Pottery Barn Teen to give them some ideas. IKEA is another good source for ideas and accent pieces for teens. I'd let their separate personalities have free reign with their choice of bedspreads, decorative pillows, etc. Put up a large corkboard for each girl to pin up stuff that is important to them and remind both they can express their individuality by hanging up posters, etc. Perhaps DD who loves bright colors may be content with a more sedate wall color if she can put up some colorful artwork. It may look jaring to you, but what is more important is that they love it. As for sleepovers, I second Les' suggestion of aerobeds. I have a twin and it works great. If there is more than one child sleeping over my kids would go in the family room anyway and use sleeping bags.

You can get a headboard the same color as the dresser, and match the night stands with it. And based on the photo below, you can use the grays tones instead of the green. dark gray sheets and lighter gray on the walls, with some decoration in wood style. And do the decorations on the blue that she wants, with pillow, a rug, curtains...

I just do it in PowerPoint, I put key words on internet to find what I'm looking for and simply copy the images I want... To do it yourself, just copy the items you like and assemble them on a page. That will give you an idea of how it all looks together, doesn't have to be in aa room setting.