And for some other suggestions, how about extending the base platforms out from the city towers to create docks? Then flood the center area with water, put a few futuristic ships in the harbor (with the odd loading crane, etc).
Actually, can I make a suggestion? Sink some of the buildings into the ground so that it staggers their height. The problem is that they same building models are all the same height, making it look like there's been a lot of cloning going on.