Some photos can be processed either way and will look good in both. Others will only look good in one or the other. I guess for me it is more of a feel when I see the photo. Some people go out to shoot one or the other and in the film days we had to. Well there was a way to print black and white from a color neg but I never thought it looked all that great. Of course it could have been my darkroom technique as that is something I only did a few times.
The above photography, I think, works equally well in both. It really is a personal choice. I had to do a bit more burning and dodging on the black and white to make it look as I liked it.
The second I saw the above scene as I drove over a hill in Colorado I knew it would be black and white. It just had all the qualities that I like for a black and white image.
The above image actually looked good in both but I chose the black and white to create more of the mood I thought a bare tree in the fog was showing.
I think the old saying is true that you have to do a better job of composition and the technical aspects of photography for black and white because very often a color image can get by on the color alone.
This image above in color just would not make it. Black and white was the way to convey the feeling I was looking for. This was taken a few years ago on the day, okay one of the days the world was supposed to end. I wanted to portray the solitude and loneliness such a prediction can create in someone who had no family or friends to cling to if it truly was the last day. Of course my wife and I were together and went over to Voodoo Donuts just before snapping this maybe a block away.
Here is one that works equally well in both color and black and white. It is interesting to not the entirely different mood given by each one again showing the power of each medium.
If you have not tried shooting black and white go out and try it. It is a wonderful medium for expression. Back in the film days black and white is kind of what I was known mostly for. I loved shooting it especially in medium format. The tones were amazing. I love the tones we can get with digital as well. If I were to have to pick only one processing program I would go with Lightroom you can do it all in there. I do personally use Photoshop and I love NIK Software's Silver Effects Pro I think it is the most powerful black and white program out there, well the last time I looked.