I took this because I thought it was striking the way that the diagonals were framed within strong horizontal lines. I think the tonal contrast helps highlight the difference in the lines, and also helps the diagonals actually read; I think they would get lost if the white didn't draw the eye as strongly. Something I would change is to have a subject on the stairs but, alas, this is in the back of a credit union and I didn't think breaking in for the assignment was fully prudent.
I took this because I thought it was striking the way the posts stuck out so strongly against the light background. I think there's a subtle sense of uneasiness conveyed because the dark vertical lines contrast from the natural horizontal line of light at the base of the building. If I changed anything I might get closer and cut out some of the empty space at the bottom of frame that just kind of muddles things.
I took this because I thought it was striking the way this dog was kinda just, like, chillin... or something. But I do like how the horizontal line of his body matches the restful tone of his... rest. It's shot at dog level, so the base of everything matches the horizontal and avoids any conflict in the frame. There are the diagonals from the tile, but to me they act more as leading lines to the dog than as any sort of linear contrast.
Firstly, I just have to say that your photos look great and your captions are fantastic! I literally laughed out loud. Great catch on the diagonal stairs juxtaposing with the building wall on your first one. I agree that the second photo does have an ominous feel with the way the vertical pillars are backlit. I think it might have been even more unsettling if you shot from a lower angle. I think the affinity of line is clear in your third one, as is the affinity of tone (and my affinity for good bois).