I don't convert to black and white often, but when Nik color efex pro had a b&w filter by default and it looked good I decided to dump it into silver eFex pro and give it a go!
For both images I used the filter that had high structure and contrast. I also dialed in a red filter to make the sky pop and slightly lowered the structure. When editing them in color I used a polarization filter. Not a substitute for a real polarizer, but like an ass I left it in the car :-)
How about that sky?