I think you could do a really cool abstract photo with that first building. it has some really nice lines. I think shooting it with the blue sky in the background doesn't really do anything for me since its the same color. you already get the sky/clouds reflecting off the surface. I would try to re-shoot that building corner and try to focus more on the lines of the building (corner edge, glass edges, etc), try and shoot in closer in too.
the sidewalk shot has some potential. I really like the composition and exposure, but the shadows of those two people are bothering me. I would have waiting for them to get a little bit closer, having the shadow run out of the picture just makes it odd to me. if there shoes were in the field and the shadow extended further it would work better for me. try and get the tile a little more off center and the shadows off center as well.
the last shot is very underexposed. I think the composition is nice, but there is just no interest in the foreground. it would look nice with a nice long exposure to soften the water/waves. but really you need to increase the exposure significantly.