Always remember the 2:3 rule when placing hardscape (this according to Takashi Amano). Always place your hardscape so that there is an unbalanced look to it. Natural aquascapes do not draw the eye toward the center but draw the eye toward where you wish it go. I know it sounds like some stupid thing Tom Cruise might say in a crappy samurai movie, but look toward unbalancing the hardscape. It's hard to do because your natural tendency will be to balance things. Amano always says to plant in threes. I subscribe to this principle as well.
OK, this isn't making much sense, but I've been working on something according to his principles lately and I have to say it doesn't look too bad. More later . . .