Please keep in mind that, ultimately, what you like is what you should do with your tank. You are the one who looks at it everyday.
That said, if it were me, I would take more advantage of the vertical space. Something of varying heights between the left and right sides of the tank. Arches are great, and we tend to think in terms of symmetry, but I'd encourage you to branch out and experiment with asymmetrical configurations. Google some top design tanks, and you'll see what I mean. Irregular shapes and patterns are more interesting to the eye, and take your eyes to different places.
Please feel free to post some update pics if you try out different things!
Welcome to the hobby. Looks like you're off to a great start.