A Centropyge angelfish Angels
would make a nice centerpiece fish for you, and give you something with a touch of size. The Coral Beauty, Flame, and C. argi Pygmy angel would be a good place to start.
You could also keep any of the smaller Wrasse species, such as the Carpenter Flasher Wrasse or Six Line Wrasse.
Obviously you will be able to keep smaller Clownfish, such as the Ocellaris, as well as Blennies, Jawfish, and Gobies.
You can actually have success with some of the smaller Hawkfish, which are easy to keep and often overlooked. The Falco Hawk, Flame Hawk, or Longnose Hawk would be grood options. Hawkfish