one thing to keep in mind is the shape of the tank itself. you have a tall tank that is designed to be viewed from more than one side. i have found that the "mound" design works best in tanks like yours: place the plants and driftwood near the center of the tank, and leave a empty circular area around them (or some variation on this theme). it looks like you have more of a "U" shaped setup, wich is really more suited to a longer tank. in my humble opinion, the Takashi Amano books are a great place to find ideas for aquascaping. until i read his books, i spent a lot of time rearranging my tanks trying to figure out why they didn't look right to me.