Will this be your own residence or will you rent it out?

It's a coachhouse apartment on top of our garage. We won't live in it, but we won't rent it. We use it as a guest house/office.

IMO a floor plan marking which walls will be accent might make it easier to understand. IMO an accent wall is best when it is confined to one wall with not openings in that wall and to add another accent ( wood slat ) to the mix is not a good idea . I do not see wood plank on those ceilings so is that something else you are adding?

Since there won't be a lot of wear and tear on a guest house/office, you could use wallpaper. Use the wallpaper colors as a jumping off point for accents.

without seeing the whole space and how it relates to each other... I would ditch the slats idea.

Apartments can be small, keep it simple, not a lot of contrasting things.

Decide on what you want to be the focal point on entering the apartment.

IF the pony wall and eating area is to be a feature, focus on that.

As far as artwork, Buy/display what you like, don't worry about whether or not it goes together, especially if you aren't seeing all of the diffferent works at the same time...

example: Think of hanging a statement piece on a wall in the lounging area, if when you look at another space in the apartment, you don't see the first piece at the same time, it can be something entirely different. Like something directly in front of you as opposed to something directly behind you.

Here are some additional pics, and a not-to-scale floorplan. All of the furniture and other things will be gone, but the living room wall color (BM Dove White) will stay the same. The plank ceiling is also white. So I can add color and texture using furnishings, but I thought an accent wall might be a nice idea. It just seems SO WHITE right now. Plus I need to put something under the bar area that is hardy enough to handle scuffs.

PS: The apt entrance is through the left door in the kitchen.

Cute guest house! Consider painting since the bar area won’t get a huge amount of wear and tear. I’d only paint the one area, keeping the left side in the current color. Add prints in your style with colors that pull that accent wall color to that left side.

@Emily posted a great option for solving your scuff problem.

I'd also paint that back patio door wall the same color you choose for the pony wall, draws you into the next space.

I like the idea of using wallpaper here.

No accent wall. It just looks so white because it isn’t furnished.