I'd like to say it was skill, but you know, i'm lucky at times. I don't actually go through the thought process of retaining detail...it just kind of happens. shooting 2 stops under works a treat for me and RAW processing is my other weapon of choice. my third?....the gradient tool in PS 8)
as you'll already know, and it's evident in your sunset/rise images the use of curves is a powerful tool to darken areas whilst not "blowing" other parts of the image.
I'm by no means a master of PS or RAW conversion, but i have my ways of doing stuff which work, similar to my Tanks I suppose.