ShiroKuro, have you spent enough time in your house/the geographic area to know what the light is like at different times of the year? I love the black-and-white triptych, but where I live now, something of that size and color against most light & neutral wall colors will feel sterile in the winter. We have unusual light where I am - it's mostly grey and cloudy all winter - and people who don't know the area often choose colors that they end up hating 5 months of the year. What seems perfect in the summer ends up feeling institutional and life-leaching when people are desperate for sun. My advice to new people here is to wait a year, if at all possible, so they start to understand the light. YMMV.
Separately, if you often play while looking at the walls, I'd prioritize finding a piece that keeps you in the right mood for practice. (I'm in the same spot as you now - trying to figure out what to put in that large space above the bass side. But since I'm very visually-oriented and (currently, but hopefully not permanently) highly distractible, I have to be careful about what I put up there. I personally would find my attention being drawn too easily to both of your concept pieces.)
Also, if you sometimes like to play with the lid up, and the big wall is what people see first, you might want to think about the interplay between the open lid and whatever artwork you have up. That long diagonal line from the lid against some vertical and horizontal elements (especially if they're coming from the dark-edged lines of a frame) can work for or against you; it really depends on the piece. My initial thought re: the triptych was something along the lines of Rubens' comment - visually it sort of overwhelms the piano. I'm not a fan of bland, myself, but that combination makes me feel like the piano is a bit of an afterthought. I don't think it's the size, or even necessarily the color, but rather that the black brushstrokes are so thick in comparison to the piano legs. IMO, if you had nearly the same piece (size, color, location of the brushstrokes) but the lines were much, much thinner, it could work quite well. This isn't quite what I'm thinking of (it's too curly and feathery), but perhaps something more along these lines: https://news.cornell.edu/stories/2020/05/immersive-calligraphy-johnson-museum.
Or something in this general direction, in large scale: (the balance of broad to thin strokes is very different)
https://fineartamerica.com/featured/enso-circle-with-calligraphy-hanging-scroll-taisho-era-nakahara-nantembo.html
https://fineartamerica.com/featured/snake-calligraphy-oiyee-at-oystudio.html
https://fineartamerica.com/featured/sakai-hoitsu-gajo-pl12-sakai-hoitsu.html
https://fineartamerica.com/featured/horse-calligraphy-oiyee-at-oystudio.html
I say large scale, because I think keff is right - it makes the room seem bigger, at least from the doorway. Also, I think the fact that the triptych extends well past the end of the piano works very well - that long horizontal line makes the piano also feel longer, visually.
Hm...I don't know if you ever visualize music (not the score, but abstract images); right now I'm wondering what you'd come up with if you were thinking about Sakamoto's "Energy Flow", done mostly in black-and-white across a large triptych.
Anyhow, art is so very personal - no matter how much other people love something, make sure it's something that makes you happy, too. 🙂
