4 different diagrid-based skyscrapers. Simple shaders applied. One building uses bevel for the wireframes and has a basic interior. Change the fresnel value for the windows shader and try with a HDR environment, will improve the visuals a lot. The model comes with an OSL based sky shader from blenderartists.org (user: br1992). Use HDR instead and you can render with GPU.

The blend includes my model of the famous Al Dar HQ building.

References:

http://skyscrapercenter.com/abu-dhabi/hq---al-raha-beach-development/4950/

http://www.archdaily.com/240524/al-dar-headquarters-mz-architects/