Hi Melissa!
I love the Ikea lack shelves...
Http://www.ikea.com/us/en/catalog/products/60103750
As a way to accessorise an entire wall. You can hang a few of them low- around 30" from the ground where a chairrail would normally sit- side by side creating a band, and then lean framed photos or art, some low stacks of books with vases or other accessories on top of them, and different layers of large scale and small scale items to keep it interesting.
Or you can hang them on top of each other with about 12" in between to create the look of a cleanlined bookcase to break up a larger wall.
Art can be so expensive, but I like running smaller photographs in black and white, and them framing them in extra large mats. That way you get the scale you need, without having to source any substantially sized piece of art.
: ) KC