First, let me say that I am in awe of the ability to paint such a piece, and I wish more of my students had the kind of talent you demonstrate. That being said, I do have some thoughts pertaining to works such as yours, and also generally applicable; you give me reason to voice them. This is not at all meant as a criticism of your work, but as something to consider for future work.
Very few cities are hatched as a unified whole. Notable exceptions are Brasilia, by Oscar Niemeyer, Chandigarh, by Le Corbusier, and to stretch, perhaps the master plan of Washington D.C. More often, the city is an evolved form, and this is reflected in the building archetypes found in both horizontal and vertical strata. Take Los Angeles, for example: There is a downtown core, which is actually two distinct parts; there is a dense urban fabric near downtown; a sprawl of suburbs comprised of single family homes, apartments, and retail; regional and local shopping centers; several secondary high rise business clusters; major thoroughfares, freeways, viaducts, rail corridors, and so on. This development has taken place over a hundred plus years, and the architecture reflects it. As an example, the downtown consisted of mid-rise buildings up until the 1960's, with City Hall being the tallest structure. Office buildings reflected the prevailing ideas of the city fabric as so often seen in pictures of Manhattan, complete with podium first floors, cornices, oversized entries, carved stone ornament, etc. When the decision was made to move the financial center to Bunker Hill, the archetype changed to the International Style brand of Modernism found well, internationally. Buildings had reflective glass from base to top, often concealing the distinction between wall and window found in the older areas. This was also matched by an increase in height and a corresponding greater number of stories. The older section of downtown was left to the non-white minorities as a no-mans-land, buffered by Little Tokyo, China Town, and the industry found to the east.
Only recently has the development spread south and east from Bunker Hill to rehab the older sections, reaching down to the Staples Center and anchored by the University of Southern California, and in infill loft housing in the aforementioned city fabric. Of course, this is a simplified explanation, as the build up of the freeways, the shift from a manufacturing to a service economy, and a hundred other factors have played their part.
The point to draw then is that the city or section of is a gradually evolving process. We can create a city digitally as a hatched whole; however I believe that under most circumstances, we should not design it as a monoculture of architecture. The more we build of something, the more we investigate variance in the design. Additionally, climate, geology, available materials, and available transportation affect the nature of the fabric of our built environment. Digitally, we need to design the evolution of the place before we design the buildings. We also need to design the evolution of the culture and transportation as major influences on the architecture.
I am not saying that we need to design and draw an entire world before painting one matte painting. What I often have my students do as an exercise is to list the characteristics of the culture or of like societies if the design is fictional. This may start from a philosophical, economic, or religious base and branch from there; how they arrive at a societal bullet point list is up to them. I believe that the more we describe the visions of cool that exist in our head in a fashion that can be easily understood by others, the more successful the final product will be. Additionally, in my experience, the more the idea is pronounced, the closer it seems to be to the original cool vision we have.