First of all. This is an amazing sized tank. I absolutely love the stand too.
You have some fantastic pieces of driftwood to work with. I have two friendly suggestions. First, if I owned those marvelously branched pieces of driftwood, I would flip those things upside down to make the root systems look like tree branches, and tie java moss to them. But that's just my personal quirk... I totally love the - "how in the world do you have a tree growing in your aquarium" look. To flip them inside down and hold them in place, you may need to mount them to slate.
Second, regardless of whether I flipped them, I would cluster two of them close together and leave the third far away.