When it comes to living room wall decor ideas, a gallery wall is a classic choice. Nailing the look can be difficult, but this modern take couldn't be easier to complete. Invest in a set of matching frames (we recommend a set of 4, 9, or 16) and hang them in a neatly-stacked grid. Fill the frames with family photos or a colorful series of posters inspired by your living room color scheme. Pick two or three colors from the framed artwork and repeat them around the room with soft furnishings…