O.M.G. I grew up in VN. I never saw windows like that. Our old house in SG was a French colonial style villa with large French style windows. I never saw a mattress or carpet until I left VN. :-D Things have changed so much. Is this attic room in one of those skinny rowhouse that pop up everywhere in VN? Where are you in VN? Okay, sorry for my excitement. Now, back to the topic at hand, I probably would go with woven bamboo shade, or make a fabric roman shade, or the easiest way, simple panels on a rod. Can you open those windows for fresh air? Please show more pics of your house. I'm so curious to see how the decor has changed! Growing up, our house decor was very French colonial, lots of dark teak, and bamboo, sheer drapery panels. Though my GF had a French iron bed and some French antique furniture left from her French brother in law . When I came back for a visit 15 years ago, they still have all the decor intact, exactly as when I was a baby! Such a big difference from America where things are more disposable, and trends come & go so quickly. I wished I can come back to VN again before there's nothing left of the past. Things probably changed too much & what's there now is nothing but a shadow of the VN I remember & love.

Wow...are you sure a question like that doesn't require a site visit? Seriously, if you don't need coverings for practical reasons, don't bother as the room is beautiful. if those are single glazing, you might wish to have roller blinds fitted against the window and hidden by trim work painted to match the window trim. You would lose a few inches at the top but a talented trim carpenter could make them look almost like a part of the window trim. I could see custom made radiator covers that would mimic the wainscoting would turn those obstructions into a desirable feature. For the top use the same profile and dimensions, at the same height, as the window sills. Columns on the ends and probably three panels of approximately same proportions as the existing ones across the front of the radiators would work well. Do some research on radiator cover design as you need to have good air flow coming in from the bottom and exiting at the top and a properly designed cover will actually help, not hinder heat distribution from the radiators. Despite the term, more heat comes from convection than radiation and channeled air flow will increase the heat transferred to the room. Let me know if you need a link to info about radiator cover designs

You could remodel that hearth and do away with the part near the window :) I like the idea of hanging the panel on the left side of the window and just living with the weird drape over the mantel when they are closed. But I think I would put up a ceiling height valence and do wood blinds. You can change the fabric of the valence as you wish to change the look and the wood blinds are gorgeous and give a room a nice feeling.if you are worried about the height of the blinds then do the top up/down honeycomb ones in a similar color to the walls to make them visually smaller. The window will still be the star of the show and the valence will be the supporting cast that draws the eye.

The shades on the doors and windows don't necessarily have to match, but they should be coordinated. If you go with a woven shade or a Roman shade, you can get those products in a vertical application. Hunter Douglas Vignette shades and Woven Woods shades are available in both horizontal and vertical applications, so you can use the same fabric on the windows and door.