Nice of you to put such specific consideration into their needs! I would think that timber blinds or white timber blinds (venetians, which are much cheaper than shutters, but can look just as good. Because they are easy to clean, but mostly because teens tend to hide out in their room, sometimes this turns into a cave and they don't really care about opening the blinds each morning, also, they are particularly concerned about their privacy and sense of space, having blinds means they won't ever look messy and the most you have to do is open them up, and if they are tilted a Articular way, they still provide them a private blockout while letting the directional light in. I would also do a timber floor for a both, as they are likely to traipse in wearing shoes that of course are full of stuff from their adventures. They play sports, may spend time outdoors and timber floors scan be easily cleaned, carpets are ruined. As for a girl, if she has different interests, or spends time in her room often, a carpet rug on a timber floor. Rugs can personalize a space, so they have some saying the decor, and easily replaced, maintaining your timber floors beneath, while providing warmth and comfort. Even if covered mostly by furniture, the edge of a rug underfoot will feel more comfortable than not.

I actually love the combination of timber, jute, rattan or patterned blinds with white sheer curtains. It's especially lovely if you want the option of either blocking light or letting the most in without letting your windows look too naked. These photos may help you decide:

Sounds fascinating but I can't see any photos yet. Maybe try to post again.

my suggestion has an ens and wiw and uses the old bedroom door for a linen cupboard, although the toilet could be placed at either end to be closer to the original sewerage, this arrangement allows for more privacy for the toilet, more standing room near the shower, wall space for a towel rail and room in teh wiw for a chest of drawers..the vanity is over 2m long with cabinet under the (one or twin) sinks and open shelves next to the toilet for towels .. and, while you're adding the new ens, it would be worthwhile to plan the new access to the kitchen and new laundry