Just adding to the other comments:
I always found that b/w has this great opportunity to play around with the dynamic range. Images that would be far too saturated, contrasty and/or brilliant in color can actually work very nicely when converted to b/w.
The downside of using b/w is that the image can look flat, even if the actual subject was very colorful. If there is no light, or contrast to make up for that flatness, I would like to see something else to draw me into the picture - something for my eyes to focus on, be it a blur or movement, a twinkle, a hint of light or another nice point to focus on.
Most subjects work well in b/w and color (even things like flowers etc), but b/w needs extra work to create the oomph.
The image of the aspen for example I think can be easily turned into something nice and attractive with some dodging / burning and contrast localisation. Get those leaves off the background and make them sparkle. Same with the stone in the water. I don't think at all that these images are dead - they just need to be watered.