Scott,
; ; I did not use an ND filter, I exposed for the castle and set f/14 so it would expose a little longer. It was a single RAW shot and I did 3 runs through Adobe Camera Raw with the same shot so that each part of the shot would be exposed the way I wanted. I then used layer masking to punch through to each layer I found most pleasing. I flattened the 3 layers and then used detail enhancer with NIK Color Efex ; and again used layer masking to only use the parts of the NIK layer I found better. Last I used some sharpening and noise reduction where I had to.