You could do any softie, I don't know much about LPS and SPS so hopefully one of the people here that have experience with them can chime in, but zoas, ricordeas, mushrooms, cloves, would all be a nice addition IMO. Good luck with what you decided to do and keep us posted and if you have any questions feel free to ask.
Very nice rock work, do you plan on the tank being a reef? A goby would be nice, or one of the different shrimp species would work very nicely with what you decide to do.
i would remove some of that rock. leave some more open spaces in-between them and youll have much better flow and a lot less dietrius buildup. also leave space behind and to the sides of the rocks.