I don't see a blank wall, I see a nice view outside and what looks like remote control cell shades (?). They look very nice themselves and if you add drapes in those darker colors it will be a heavy look. I just think they'll look odd hanging over the stairs. The tiny bit of floor under the windows will look very crowded and the fabric may still hang out over that since most curtain rods project at least 4 inches and certain fabrics flare out even more.

I would not use brown blinds.....they are very cavelike. You could use white cafe curtains on rings. They could be closed after dark but kept open during the day. They are a very sweet look, too.

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

few suggestions for the bay window. individual shades are one option. (woven woods, cellular, roman, solar, etc) Another option is doing a window seat with cushion/pillows and having drapes pull across the whole thing. Or you can do individual shades. BTW, instead of getting a useless blind for the transom window, why not do an insert of some type? stained glass, leaded glass, combo of both,, ,would be pretty. would look something like this (I gave you a blue/green glass beachy design) with woven wood blinds and white drapes. (see below for more info on the window dressing) You can design whatever you like (I have a link to the girl I used on Etsy if you like) I did a stained glass insert over my own window in the bathroom. it's easy. held in place by clear silicone. you have the glass insert made to order to that windows dimesion. Yours would be super easy since it's fixed. Mine opens and closes here are examples to all of those celluar shades w/a window bench curtains w/window bench (BTW, these aren't difficult to DIY) Roman shades woven woods w/drapes for the bay since you mentioned coastal, I really like this room, especially the beaded light. you have the height in your ceiling for something like this. Love the board and batten panels behind the bed too. looks great w/the white textured rug and woven ratten elements. Another way to do the batten panels. this is pretty easy. just run them up the entire wall. paint white and do the other walls in the seafoam (like shown here.) Bring in the beaded light (or a fan) and try a sisal rug. another coastal idea. roman shades on the window Vertical panels behind the bed with a long shelf. put up beachy items to display navy accent wall with white plantation shutters on the bay another bay window (s) with linen style roman shades. love the woven rattan ceiling light, comfy chair by the window, potted plant.