There is an excellent pair of blog posts by Ivo Sucur covering the full process he used in creating these images of the GH House (part1 and part2). This is all on the Ronen Beckerman blog which has a host of other Making-Of articles - outstanding resource for Architectural Visualisation actually.
Here are the 2 images that Ivo takes us through his creative process for. I like the less formal approach taken here of the Architecture under construction, rather than the oh-so clean visualisations that are standard fair.
[Ivo Sucur GH House Visualisations via ronenbeckerman.com - shrunk]
Here are a few more visualisations to inspire a closer look at Ronen Beckerman Blog. This time by Ronen, Fietter, Celestino and Anton.
[Visualisation Imgery via the Ronen Beckerman Blog - shrunk]