I like both pieces in their new locations and just love the painting over the mantel! The light green pillows look nice with the photo but the smaller chevron one is a bit distracting. Agree with it's being moved down and placing two smaller, similar photos framed similarly on either side of,the dandelion.

Thanks for the comments. A vented FP isn't an option. This is a condo in a high-rise; each unit has a ventless gas FP. We are replacing the existing one, which is broken, 16-years-old and pretty ugly. I have read up on ventless and had a long conversation with the salesman at the fireplace shop, who was extraordinarily helpful. He told me that Empire is the only gas ventless they carry, because of the care you have to take with this type, and because Empire's quality is exceptional. I am comfortable with this brand, and would open a window when using any FP in any case.

Literally all that is coming into my head is religious icons (something about the arch over the fireplace is evoking an altar to me). Since your living room is not a church, I would probably go with the drywall option. It will give you a lot more flexibility.

I also want something that's going to work in the space. If by “work” you‘re thinking that the colors need to match or coordinate with the other elements in the room, get that notion out of your head, please. Art is not decor; art is, well, it’s art! In addition, @User’s advice is spot-on: “Shape and size would be secondary considerations. Certainly the scale has to work, but choose the ART first.” Bottom line: Choose something you love and it’ll work. More importantly, have fun with it! ;)