Using the free GRFX Studio Serge, I replaced the sky in the above image. The day we took this photograph, it was grey and dank and the image had a dismal grey sky. Using the free software in Photoshop, after merging the panoramic shots in Photoshop, I add the very dramatic sky.
Once back in Lightroom, I did a few brush strokes to highlight certain parts of the image and softened the water. I really do love the drama this software gives you when replacing the sky.