Yeah, try to build interesting shapes with the rock. Make a cave or have overhangs leaving areas shaded. A little more rock would be nice maybe trying to hide the powerheads to give a more natural look. Take a look at pics of other smaller tanks and see what you like.
BTW As your tank matures coraline and algae will give you live rock a consistant appearence but I still prefer to use the same kind of rock throughout the tank.