Following this symmetrical formula is a simple and guaranteed way to achieve a visually pleasing arrangement. A few more examples from some of my favorite designers to illustrate some of the many variations on this theme:
If you have a longer wall to fill, follow the lead of Miles Redd (above) and Sally Steponkus (below) and try flanking the console table with a pair of smaller chairs. When company comes, you'll have the extra seating, but otherwise the chairs will be out of the way for day-to-day activities.
If you're trying to break up the symmetry a bit, I'd suggest keeping at least one element symmetrical, as Ruthie Sommers did here with the pair of sconces flanking the mirror. This is a simple trick to bring balance back to an asymmetrical space. [Random aside: Did you notice the adorable dog lounging on the stairs in the mirror's reflection?]
Sometimes a simpler, less cluttered arrangement is best, particularly in a small entryway or hallway. Here, Lindsey puts the emphasis on the vertical space of the room rather than the horizontal by using highly reflective elements (the metallic wall paint, the gilt mirror, the glittering wall sconces). The effect is further realized by placing the mirror and sconces higher up on the wall. A word to the wise though: when hanging wall art, mirrors, sconces, etc. it's best to keep them below the height of the door or window frame.
Time for the masters' class! In this vignette by Tim Clark, nothing is symmetrical and yet the arrangement is still highly successful. The red rattan chair is balanced by the palm in the red pot and the height of the pot is similar to the height of the floor lamp behind the chair. The green stools echo the color and shape of the small vases on the opposite side of the console table. As each side speaks to the other, the eye moves back and forth across the vignette.
A final point to consider is that sometimes fewer, larger pieces are far more effective than a bunch of small tchotchkes. In this vignette by Amanda Nisbet, the scale of the mirror, lamp and bust create a lot of drama without creating a lot of visual clutter. The neutral palette also ensures that these disparate pieces work harmoniously together.