Thank you all for your insightful comments! The main reason I post on forums is to get the various perspectives of seasoned photographers; this website and forum has certainly shaped my photographic knowledge and interests over the years.
I do like the landscape orientation that Alain posted; that is something that I hadn't visualized while shooting. After a side-by-side comparison of the vertical Vs. Horizontal, I am still attracted to the vertical one. I did think (and try) B&W, but the hint of color in the branches and the horses is what attracted me to the scene in the first place, so I decided to stick with it. The reason I had stopped and gotten out of the car in the slush was to somehow capture the minimal color in the vast white expanse. I've scaled back on the grain further (I wish I could add grain with the adjustment brush to give the snow more texture) and will play with the other levels while printing.
