Hi BrownBread. If that was my tank, I'd do this:
Replace the substrate with sand (ok I admit, I'm a fan of sand in tanks, so sue me.
), but leave small patches of gravel on the surface of the sand, to create a kind of river tank look, which the smoothed pebbles help acheive.
Next, I'd move the right hand side of the left hand peice of bogwood backwards abit so as to create a little more depth. Try putting it on an angle and have plants growing under and around it?
I'd also clump all the vallis looking plants in the back left and back right corners, as they will help visually frame the tank. Next, I'd clump together the other two types of plants (cabomba and something else I don't recognise?) into two bushy, well groomed clumps. I'd introduce some smaller plants to dot around the aquascape like some of the anubias', cypts or e. tenellus. Looks promising!
Thanks,
Chris
EDIT: Also, on a side note, I'd seriously NOT have that airstone on. The air bubbles cause the CO2 levels to drop, which will either (a) counter the effect of added CO2 OR (B) deplete all the co2 starving the plants.