I took this in Petrified Forest National Park in Arizona. It was around 100˚ when I took the photo, and I don't think that the colour version of the photo really shows that, wheres the black and white version does. I also prefer the black and white one because it adds a sense of loneliness; something I think that Black and White is very effective in expressing.
A more recent attempt demonstrates this to a greater extent. This is the view from my university room, during the irritatingly-named "Big Freeze" of early 2010.
I like the colour version a lot; I think the mix of the brutalist architecture and the solitary character make it feel quite lonely already, but I put a black and white effect on it, played around with the blue colour levels, the exposure, and the contrast, and I ended up with this:
I effectively just made the photo darker, but I'm really pleased with how it came out. The buildings and the trees contrast with the sky more effectively than in the colour version, and the character in the picture draws the eye in now that he's much darker than before.