Thanks for the great comments. When Karen Randall did one of her talks here in Seattle on aquascaping and what the judges for AGA look for in the AGA Aquascape Contest one of the principles she emphasized was using contrast to create drama. The more contrast, the greater the dramatic effect.
I tried to incorporate that suggestion in this aquascape by using three types of contrast; color, texture, and form. In this layout there is contrast between leaf colors (reddish vs lime green), leaf textures (smooth vs crinkled), leaf shapes (long vs roundish). You can't see it in the photos above but there is also contrast between the various plants and the stone hardscape.