Shiela your understanding of the principals seems to be perfect to me. Tom as you said appropiate metering is the key. I agree with Shiela I can see no reason why the principal is any different from film to digital. I try to meter the scene to give me the tonal ranges that I want, I also work the image in PS doing what for me is a standard workflow on tonal range to give me the result I am looking for.

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html