The right side looks great. The left side is almost there. Maybe work that top-right rock into an arm that reaches to the middle of the tank. I'd try to flip it so the fat end is toward the structure and the narrow end reaches out. You may have to build it out with other rocks, glue and epoxy putty. I'd also plan to put a small island in the center. That could be as simple as a couple of rocks half buried in the sand, sticking up a couple of inches. It'll be a great place for zoanthids, acans, favites, and maybe some eyphylia in the back for height. I'd angle it so the back is off to the left and the front is to the right. You should be able to work that out when you put the structures in the tank. You also may want to put the two big pieces a little more towards the center, but you can work that out in the glass. Remember, you'll want to put coral on the outsides of those structures. They'll grow out into the glass and make it hard to clean.