Suggest a nice large pice of wood, or several smaller pieces of wood would make a nice focal point in tank, along with more stem plants at rear.
Java moss or a moss type plant on the wood would be good too.
Java ferns would make a nice addition as well.
Also if you do not want wood in that the due to tannins and suchlike, maybe rocks or stones arranged as a focus point would be cool as well.
One last thing, perhaps changing the background poster for a plain colour one, like black or blue for example, will bring out the plants more as well as the colours of the discus fishes.
Lots of things you can do, just use a little imagination and you can do anything you want, even a sand waterfall if you want
