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.

I think this is one of these things that should have a "post-game analysis" of sorts. I don't mean to be critical, but this will be analytical and it may help someone else who builds a house in the future. The idea here is nice, and the essentially linked windows are similar to a true palladian window, with the tall window in the middle and subordinate windows on either side of a height equal to the bottom sash...fine. But you've kind of backed yourself into a design corner because these particular windows need to be covered, and yet you don't want to cover them too much, or all the time. A palladian window in an 18th or 19th c house would be treated like this: The walls would be thick enough that shutters would fold over the small windows and fold back into shallow pockets in the jambs when you wanted them out of the way. The larger window would be elaborately draped because of the curve or possibly mostly left bare,depending. If you were to design this over again---or if your architect does do this again in another house---a peak that was wide enough to allow a single rod or top mounted treatment that was wide enough to cover all three windows completely should be one thing considered, or more room for shutters to be folded back would be another, a shorter or differently proportioned window in the middle another. I think that windows are often designed as if they can all be left uncovered because nobody's windows need to be covered for privacy or light control. And really the opposite is true. Almost Every window should be designed if it will need to be covered for privacy or light control, and if it doesn't great, but if it does you are not faced with several less than ideal options and possibly some really awkward options but no perfect options.

1st I would paint the blue wall in the DR the same color as the other walls. In DR I would hang panels on each window. Hang the rod 1/3 of the way down between the ceiling & window top. In the LR treat the 3 windows as one although I see that may be problem due to the TV placement. The panels should be wide enough to cover all 3 windows