I find when I am out shooting skyscrapers it is really the sky that helps add so much more to the image, especially when converting to monochrome. If I had an overcast sky to work with it is much easier to find frame my images and add a little dramatic flare depending on the type of cloud cover.
Nikon D90 1/100 sec f/16 ISO-100 at 16mm
Nikon D90 1/80 sec f/20 ISO-100 at 11mm
Nikon D90 1/80 sec f/20 ISO-100 at 11mm
Nikon D90 1/320 sec f/8 ISO-200 at 11mm