I think an empty middle looks cool because you’ll need the sand space for small islands or colonies of zoas or shrooms. Or even a garden of euphilias, trachys, scolys, clams, etc.
Don’t be in a big hurry to add corals. Give it time to become established, not just cycled. Did you add any live rock? It helps significantly getting the tank from cycled to established.
You can always add more rock later when you fill this rock work up! I realized that is the way to go because you can then see how the corals are growing and make cool structures around them.
