Thanks all for the kind comments 
Just so you know, I've printed this at approx 8x12 w/ a white matte and hung it up, it looks awesome!
As for how it was obtained, the original shot was pretty close to this. The clouds were absolutely amazing - very dark and doomy (like you see here). The colors in the field were a great juxtaposition to the dark clouds.
In lightroom, I brought up the blacks and clarity. I adjusted the tone curve to give it some more contrast. Then in HSL, Aqua, Blue and Purple's luminance sliders were turned down and their saturation turned up. The rest is in photoshop:
I had a levels adjustment layer masked to affect only the sky, a levels adjustment layer masked to affect only the sign, and a B&W adjustment layer masked to affect everything but the sign, and it's opacity was brought down to 54%.
Hope this helps
