Are there any limitations set by your HOA?

A short, wooden fence with some nice flowers with open up the area. You might also try starting a tiny garden.

It seems to beg for a lovely flowering tree on the right hand side of the "garden" space, something that will grow tall, to soften the hard lines and hard surfaces of the building. You could also add a focal point in the space - fountain? sculpture? small bench or chair? Is the front of the building curved or is that just the photo? I would introduce a curved line, using the boxwoods, again to soften the harsh hard edges of the building. Move the shrubs (boxwoods?) away from the lower windows - come straight out from the building at the left side where the security sign is posted about half the distance between the house and sidewalk, then curve toward the right to echo the shape of the building. Behind this row of boxwoods, plant bulbs and perennials that bloom at different times so that they will provide an ever-changing floral display to enjoy from the interior as well as the exterior. The boxwood hedge will keep it looking neat and tidy. If you painted the fence in a gloss enamel just a tad darker than the building, it would all but disappear. You could use some colored pencils to color in different fence colors on a piece of clear acetate laid over a photo, and also try different colors for the flowers you might want to plant in the space and see how you like it.

oops - probably need colored markers on acetate instead of pencils...

Thanks for all of the suggestions - we definitely need to get a colorful garden going! I'll play around with different colors for fence too, as this brown is so flat and dull - it just accentuates the color of the building (which already isn't my favorite).