It's hard to tell from your photo, but in this situation I would show a client black "wood" blinds ("wood" because real wood in a bathroom can warp from the moisture.) A 2" slat would be great - particularly if you have the room to inside mount them. :)

Sarah, a lot depends on the ultimate finished look you want for the room. Search Houzz for photos of rooms with panel blinds to get a better idea. I do like panel blinds - considered using them myself but then decided the look was too austere for my taste and how I wanted the room to look. If you do decide on them, I think I would take them across the window too to fill the whole wall and give the room a more elegant look. Two different finishes can break the room up and look bitty. The second window could have a roller blind. If you are using a thermal blind though, use a double blind with a mesh for daytime to let the light in. The thermal blinds do keep light out and can make a room very dull. You could do sheers from the ceiling without recessing them - not as luxurious a look, but they will still look very nice. You would almost end up with two walls of curtains but it would make the room look very inviting and offset your heavy furniture.

It does look better if they are. But different but related eg all white, or all blinds can still look ok. But you have to live in it, so have what works for you.

I agree with Country House Girl, go with panel glides if you need them. I am currently shopping around online for mine to cover a similar door opening but only 6m wide. I hope to get a light filtering style to keep it soft - as opposed to block out. And will be tinting the windows for just that bit extra privacy and also sun fading protection. However if I didn't have neighbours I would just leave them bare