I'm far, far, far from being a guru. In fact I'm pretty much on the opposite side of the spectrum. But my favorite light to use for outdoor is the directional light to simulate the sun. I always watch the technical stuff in the special features for movies and they all seem to use more than one light.

I think they use one main light to simulate the sun (probably a directional light) and then several other lights to create the right mood and look.

I know this isn't much info but perhaps it's a place to start from.

Here's a link to an amateur render of scene I did using only one directional light.

https://erothf.googlepages.com/notepad

edit: if the pic doesn't show up after going to the link, try hitting the refresh button or Ctrl / r