My sister is refinishing her hardwood floors and wanted to go with an espresso finish. I told her she was "so 4 years ago..." and that, with her gray counters, she was the perfect candidate for the latest color in hardwood flooring, "gray."
Staining warm wood tones gray doesn't actually come out "gray"- especially in the lighter tones, but the hint of gray is that hint of the unexpected that creates a really beautiful look.
The species of wood, the intensity of the stain, and the variation of the plank coloring can give the gray very different looks.
This color is called "graphite." It is certainly more modern- a strong look.
The color above is more specifically what I imagine in my sister's place.
To further blend her existing warm tones with the gray- I would use her backsplash as a unifier. Something like this combination of slate with gray glass would be perfect:
Good luck Debbie- take some good before and after pics for us! (even if you do go with espresso)
Hardwood from Armstrong.