If you do decide on curtains, I think theresa's idea is interesting. The only problem I see there is that the outdoor fabrics tend to be quite heavy, and for such a big window, I think you'd have too much bulk and weight to make them work inside. But building on her idea of tying the window to the view, and depending on your style, what about considering lightweight nylon sailcloth or parachute cloth? Those billowy fabrics come in very wide widths, you can put a lot of yardage on a traverse rod - or a regular rod with grommets - without weighing it down, and you could stack lots of it to the sides without creating too much bulk.. And where you live, you ought to be able to find a sailmaker who can get the material and make your panels. If you want to consider that, the way to make them feel more homelike is to make the panels with very deep hems - 10 or 12 inches, I'd say. You also might need to add a light weighting chain in the hems, to keep them hanging well, but I think they could be very pretty and effective.

I have similar windows but mine are not quite as wide (79") and I believe they aren't as high. I currently have "make do" curtains across them until I decide on window treatments. In the primary bedroom (i just can't call it a master at 9 x 12), I am torn between shutters (which I would attach to trim which we'd add) or linen roller shades with curtain panels. I like the idea of panels to soften the small rectangular room but I love the clean look of shutters. In the spare rooms (one is being converted from storage to a dressing room-- the other is in the process of being converted from a spare room to an office), I will do either fabric roller shades or custom shutters. As you can see, I have no trim-- typical modest mid century ranch style. I do plan to put trim around all the bedroom windows. Here's a photo of the short wall (work was still being done at this point-- painting and floor refinishing. I have not yet replaced the hideous closet doors.) I really like this look with blinds.. simple and clean.. nothing to catch dust. But this room has one window with panels and one without. I'd worry that two without would feel cold or institutional.

Have you thought about bottom up top down pleated blinds or honeycomb shades? Minimal in design and able to install as inside mount to a shallow depth of only 1/2 inch. Here are some client pictures and how they solved their bay window challenge.

Looking at your setup from that second angle suggests you’d have proper clearance on the left but now I wonder about the right side The space on the right is limited by the protruding fireplace “trim” (the mini “hood” above the fireplace opening and the detail below the opening). To see what might work you could purchase a 96” or 104” drapery panel, (whatever appropriate length) hold it up at height rod would be, and see if it hangs ok. Does it look squished, left to right by the fireplace? Does it hang freely? A heavier fabric panel will take up more soace, especially if it’s lined. Maybe a cotton canvas but no lining, or a blackout panel would fit. To help you decide about adequate space, consider the function of the slider. Do you open it a lot? Is that outdoor space a spot you use all the time, or does the door stay primarily closed and youre not going theough that door much. The right panel could hang partially over the door handle (door seldom opened) or it could hang so it fuly clears the door handle (use door all the time). Alternatively, you could mount a shade over the arched window that is long enogh to cover the sliders when shade is let down. (Prob requires a custom made at this length). Whether a shade or drapery, the slider door handle and limited width and height of space will inform your decision as Im sure you already know. Either woud work, but neither are ”perfect”. But perfect is seldom needed. The pros have great advice; maybe they‘ll weigh in