It's a little evenly spaced, and a little too symmetrical,id reccommend you shorten one of the rock stuctures and maybe put a smaller rock in the sand near the bigger rock (the one you didn't make shorter). This technique Im explaining right now is used quite often in aquascaping especially in freshwater (iwagumi scapes are completely dependent on this rule). When in comes to saltwater tho, I would recommend you would also take in what corals you will use, how big you think they will get eventually,etc. The smaller rock I told you to put near the bigger rock is to Balance the feel of the scape, maybe it could be a zoa rock. Honestly, what aquascape that will be best completely depends on what fish, coral or whatever else your thinking of putting in here, could you please provide with a future stocking list (or wish list if you haven't decided yet)?