Would it be possible to hang some drapery panels from the ceiling at one end of the room, to divide it into two sleeping spaces? The divided area would only have to be about as long as the beds plus a foot or two. That way, each girl could have their own little area, and the walls in that part of the room could be strictly their fav colors for the parts of the wall that they 'own'. I am thinking this because it sounds like the two girls want very different things - one likes bright, hot colors, the other wants a soothing, subdued space. Trying to do two walls in a hot color and two subdued won't really work for either girl.

Then you could have a 'common' space, where the desk will be, seating for friends, etc. Do the walls in that part of the space in a neutral, perhaps a pale grey, and then use their colors as accents in pillows, artwork, a rug, etc.

As for sleepovers, sleeping bags or inflatable 'aero' beds are perfect. Besides, they will never sleep - they just need floor space to sprawl! LOL

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.

The Ikea Expedit bookcase is an easy device to divide a room without making an actual wall and add storage.

Why not get them trundle beds for sleep overs -- room for each girl to have one friend over? Any more than that and it's a slumber party -- sleeping bags on the living room floor.

Will you be adding a closet or 2 to the room? VERY important for girls.

I agree they should get to be part of the decorating project. It might make a very good joint project for the three of you together, but make sure they actually get to make some choices of their own. One wall color, but they should be able to choose their own bedding. When I was a teenager, I used to buy on sale flat sheets from expensive designer bedding sets and sew them together to make pretty duvet covers so that I could change the look of my room often. Neutral walls made giving the room a fresh look very easy.

Ikea is an excellent idea.