Yep, I agree with a new aquascape. If it were me I would take the rock out and rescape it to give you more room and a better look. With only the clownfish for now, you don't need so much rock for filtration. While you are doing that, I would also vacuum the sand bed. For that you may want to take the fish out for a day or so. Just put em in a styrofoam box that you would ship stuff in. Add a heater and it'll be fine for a day.
That'll give you a chance to clean and aquascape without worrying about your fish, etc.
If you think of it like cleaning and rearranging your living room, you will have a "new" tank when you are finished!
If you want somewhere go start as far as corals go, zoas are a great place to start, leathers, mushrooms, will be great and get you really involved.
What lights do you have?