Great Gill. I think cubes and spheres have their strengths. In your case, spheres are indeed better, for roofs I would say cubes/bricks are because they give a smoother border. Especially when you play a bit with the rotation slider in the ecosystem settings to reduce rotation variations.

However, good to see first results so quickly. The tutorial seems not too bad.

One day your ship comes in - but you're at the airport.