I really enjoy Sargent's watercolors. You can learn a lot about what he was seeing by looking at those quick doodles in water color.
Sargent was very inventive, and didn't like to be restricted by little details, he was more concerned with composition and capturing something more powerful. I've seen a few of his paintings up-close and they have effects and textures that are poetic and relate to the overall image.
I think something also interesting about Sargent is his way of making dark paintings seem cheerful or something other then dark and shadowy.
here's some good vids I watched the other day on Sargent.
http://www.youtube.com/watch?v=3krxe_QkXDk
http://www.youtube.com/watch?v=qPWEy78BURs