You'd paint the vent cover to match and put it on top. Same with electrical (although you'd actually move the electrical boxes forward to be flush--don't recess them like your inspiration photo).

I would think that you could have the vent moved to another location, maybe to the short wall to the right or over the doorway to the right.

It would likely be easier to move the vent to the ceiling than a different wall. I guess it would depend on which direction the joists are running.

Installing that wall treatment would make the vent less obvious, I would think. As long as the vent is painted a color to blend in.

You could cover the vent with the material but have slots or holes routed in the material for air flow. Along the lines of this:

I've even seen floor registers routed into the parquet floor pattern in house with a round entry rotunda. It can be done, it just takes planning and being able to work with the wood. You may be able to do it yourself with a smallish hole saw and just create a pattern in several of the boards.

Do you plan to match the wood floor to the wall? Are you concerned that the two woods may be too different to look well together? And, do yo have wooden end tables, coffee table or are they made of a different material such as chrome/glass?

Thanks for all your comments. The photo was more to show the air vent but the photo is from the model home so I've attached the sample of our chosen flooring. The herringbone wall idea will be a slate blue/grey, I attached an idea on this part as well. Couch is light grey and we haven't purchased other furniture/accents yet. Thanks.

Thanks.

Agree with Patricia. The herringbone wall treatment is one too many busy elements.

Another vote for no herringbone. The floors are already an assertive feature.

If the herringbone wall is a solid color, not meant to mimic the existing floor, it will be nice. Just remove the vent when the wall is being done and then have the vent painted exactly the same color as the wall. Moving vents sounds simple but these air return vents are meant to be high and it's not easy to move them.

No herringbone pattern..that does not eliminate another pattern. Consider something larger in scale, so it isn't as busy with too many lines. What ever color you choose for the accent wall, simple paint the return the same color.

With all due respect, I don't think the appropriateness of the herringbone itself was the question here. Our OP is clearly thinking through all potential issues before beginning.

Fori, I love the Herringbone wall and you are correct. The OP was asking about the vent. I think the vent will blend it once everything is stained/painted.

Vents can be camouflaged and even faux painted to match anything. That's a serious accent wall and will be the focus of your room, so what do you plan to put there? Will the intense pattern be a distraction from the architectural focal point that is probably already built into the room: window view, fireplace, TV/entertainment wall? I hope the installation you're planning will go better with your floor than that in the inspopic you posted. Have you considered just faux painting the pattern on the wall to be easily changed out when you tire of it, or when you put the house on the market later on? I would have expected the floor to be herringbone, but if you can get the same flooring to do the wall, I think it would be a more consistent look with just a touch of interest with the pattern change.

you might be better off doing a wall trim accent wall

or you could do a solid, darker color. it's shown here w/a busier looking wood floor.

this vent should have been painted the same color

you paint the vent the same color as the wall color. not a big deal to do.

Some other alternatives.

or you could do a solid, darker color. it's shown here w/a busier looking wood floor. BTW, that pic of yours w/the brown herringbone is this one. (pre-painted. she used MDF planks)

https://homewithkrissy.com/2020/03/09/herringbone-accent-wall/

this vent should have been painted the same color

It will be beautiful. It is your home and you are the one to live with your choices. I really like your floor choice and the color you plan to do the accent wall.

I like the vent painted same colour as the wall but please use the router to make a new cover as another poster mentioned.
Also I know you didn’t ask but I’m throwing this out there, you said you want slate grey floor, grey wall, and grey furniture. 😬 it may feel very cold in there with so much grey. I’m very much a “feeling” person when I enter a room. Eg. I want to feel calm when in a bedroom, or energized when in a kitchen etc.
I tend to look through photos and instead of focusing on any one element or colour, I listen to how my body feels when I picture being in the room in each photo.
I hope this helps.

I think that Judianna 20's suggestion of square wainscoting wall would look amazing and more modern!

I think once you get the room furnished, the grey floor and the grey herringbone wall will look fine. The vent cover can easily be painted or even covered as others have mentioned (with holes in whatever covers it). I've even found decorative vent covers if you have the money to spend.

My thought would be visually - grey wall, grey floor, grey sofa. The sofa is going to disappear and will be harder to see in low light or for those with old eyes. They might be different shades/hues of grey but they will visually blend. Think contrasting colors as you add in other pieces. And put some popping throw pillows and a non-grey blanket on the sofa so that it doesn't fade into the wall. If you do any armchairs, think of them as an opportunity to have colorful furntiture. Not only will one be able to see them in the room, it will help bring a little life to the space. Bonus points if the chair color is picked up by the blanket or pillows on the sofa.