What is the substrate above the fireplace? You can adhere stone veneer directly to untreated & unpainted brick, block or concrete. All other substrates require the use of lath and a thin scratch coat of mortar. Thinset can be added to the mortar to help in the initial adhesion of the stone, but is not required. We've never used it and have had no problems with adhesion. We always use lath in our stone applications. Thinset alone on plywood, wallboard, rigid insulation, etc. is not recommended due to the possibility of cracking or poor adhesion. Being in an earthquake prone area, I would high recommend the lath no matter what the substrate.

I'd pick my art first and see what colors I bring into the decor. With other accessories such as pillows you might very well be fine keeping the wall neutral Agreeable Gray.

Thanks @User It was a small local custom cabinet shop. I was also very surprised about the alder veneer. That's what they said they use for their paint-grade cabinets—which they don't finish themselves. It's a happy accident, because I love them, but agree about getting them finished professionally. Thanks for your suggestion.

It isn't just the stone that is in the mix, your dominate color in the room is the floor/slider wood tones. I suggest a gray/green: You can see how nicely the walls work with the wood in this photo. IMO, it happens it is a winner, too. with the fireplace.