I find this to be the most mentally relaxing exercise in graphic design. There is much art to the transformation. Detailed attention must be kept with regard to what personality you want to draw from the photo -- and this is especially difficult when the subject appears, at first glance, a lifeless black box. Then you see the windows. The textures. The shape of the hidden doors and seams. After some time absorbing the shots I'll start to see where, and how, light interacts with these surfaces and I'll use this as my mental guide to start a traditional dodge and burn brushing.
Although I do enjoy this, I actually prefer the freedom and extensibility of a 3D rendered model with scene. There is just so much more that can be done with a fully realized 3D model from print to animation.
Good photographic post production, if saved in the proper formats can be very extensible nonetheless. Bringing a box to life is challenging but definitely is a small reward.
