In addition to the other great answers here, I would add Gleb Alexandrov's tutorial video: How to Create a City, Covered With Fog. Regardless of whether you opt to add the fog, this is a very helpful (and quick) tutorial for creating cities.
He uses the Open Street Map add-on to generate the layout, so the angles of the buildings look very natural because they are based on real cities. And his texturing approach is brilliant.
Some screen shots from the tutorial:

