When we left the house there were beautiful clouds in any direction you looked. The first order of business was getting some lunch. After lunch the sky had darkened considerably and the great, puffy clouds were headed east. When we got to the bridge it was to the point where you had to be selective about pointing the camera to get any clouds. The shot(s) is a five shot bracket at one stop increments. Only shots one, three and five were used to make the HDR composite. It was done using Adobe Photoshop CS6's HDR Pro. Once the HDR screen came up the only thing done there was to make sure it was set to 32 bit. This gives, basically, an unvarnished image to send back to Adobe Photoshop Lightroom 4 (LR4).
Back in LR4, the shadows were opened up and the highlights brought down. To give more emphasis to the sky a diagonal Graduated Neutral Density filter was applied. (Upper left to below the bridge ironwork.) Another GND filter was applied to the rocks at the bottom to give then some heft.
Next was a trip to Nik Color Effects Pro 4 directly from LR4. There it was just playing. Open a filter to reveal its possibilities and say "hmmm. that looks like it might be interesting" and click it goes.
From there it was back to LR4 and over to CS6. The Nik'd version and the straight (yeah, right) version were opened in CS6 as Layers. (in LR4 - Photo/Edit in/Open as Layers in Photoshop) Since both Layers were different version of the same image, no alignment was necessary. With all the LR4 stuff and the Nik stuff, the concrete sides of the bridge had become too warm. The original LR4 version was too pale. Putting a Layer Mask on the top Layer allowed a compromise to be made on the concrete only.
Back to LR4 (if you don't have LR4, Adobe Camera Raw [ACR]will do the same) for a final touchup and a vignette. (A subtle vignette.)