That's very nice.
I'm trying to decide how I want to aquascape this. I can try and take it in two directions.
1) Fallen rocks look - A few large stones surrounded with smaller ones. This is the more natural look but also provides less hiding places and caves.
2) Caves and arches. I'd use the styrofoam to build an arch or two with multiple rocks fallen down to create many ins and outs through the structure.
Similar to the look on this tank but less adobe looking: http://www.cichlid-forum.com/article...background.php
Edit. I just had some inspiration. I think I know what I want to do...now let's see if i can actually do it