I haven't decided what to do with my kitchen island yet...but someone suggested pressed tin to me (Like the kind they used on ceilings). Apparently this now comes in tiles and sheets, and in a variety of colors. I saw some of these tiles at Home Depot and I was surprised that there were traditional and more 'modern' looking patterns available. I'm not sure how it would work out in practice, but I would imagine that it would be easier to clean and maintain and wallpaper, while still giving you an interesting texture to feel :)

I'd embrace it and either expose the existing brick, or else (ideally) wrap it in thin brick/stone veneer so you'd get to pick the color. Can even overdo the mortar to make it look original if that fits the theme IMO if you rock and paint it it'll still stick out but be more of a "wtf is that why is that there" but if it's masonry it's obviously a chimney and could add charm if done right

i agree with others, someting low. you have a lot going on visually, not in a bad way, but adding more visual stimulation is bordering on too much. i would do a rectangular/oval wooden bowl and add seasonal touches. Pumpkins, gourds, christmas balls if u celebrate, winter greens with a candle in the middle, easter eggs if u celebrate, fake lemons, fake green apples etc.... put another way, some natural elements.

You don't need to fill each nook and cranny. Negative space theory says the eyes need to rest sometimes. For the large wall, consider a local artist or art gallery. Also, some colleges have their own art galleries. If you don't get anywhere there, I've gotten some beautiful prints from art.com. They have a wide selection. I just buy the print from art.com and then I get it framed locally with plexiglass (safer and lighter than glass, and thus easier to hang). You don't have to be in a hurry to fill the walls. Wall decor is highly personal and each person has their own taste. Wall decor can even be a conversation starter! Besides framed prints, you can also get 3-D pieces such as an iron piece, tapestry, or a plate grouping.