I have been doing a lot of color so I like to mix in some monochrome every once in the while to make it visually different. The theme here is each of these has some sort of structural support in the image. The first one is a stretch because I really liked the reflection but there is some structural bits on the top of the reflection and the parking garage roof. Also, since I took the picture and I edited I declared it fitting into the theme.
The other two images are more inline with the theme and if I had to pick a favorite it would be the pole going up to the roof. It just contrasts nicely.
One of the interesting things about monochrome images and me is that when I take the picture I usually know its going to be done in monochrome. The image usually just has a few colors to it with a evenly distributed light and dark area. Architectural images lends themselves well to monochrome.