I like the look of this tank, with its strong vertical elements in wood, plants and fish!
When it's cycled, you might look at a school of Corydoras catfish. Some are boldly patterned, some more delicately so, but most school, and they'll do a bang-up job of keeping the top couple of millimeters of your sand stirred up. A group of hatchetfish might look good there as well, adding shimmer and movement just below the surface. In a mid-level schooling fish, would you be looking for color, or additional vertical elements to reflect the overall look of the tank? I think black phantom tets would add that for you... Mine tend to stay in the lower 1/3 of the water column, and the males spend most of their free time displaying to one another, fins at full extension.
Any way you go, it's a beautiful beginning!