My choice would be to set the 'skylight' color the same as the ambient (in real world outdoor scenes, all the ambient light comes from skylight or skylight reflected from surfaces).

For a warm look, that would be colored like your ambient. For a (rare) neutral scene, it would be white. And there is a sun color on the 'Sun' tab.

I'd also try moving that 'Light balance' slider to maybe 70% to 80% to get more sun influence (sunny day)  and the Ambient light slider to 60% or 70% for the ambient to come mostly fom the sky.  Since GI is heavily dependent on having lots of ambient, you do have to be cautious with the 'Light balance' slider. For the same reason, you could try more or less 'Artificial ambience' as well.

And for the final tweak and render, i'd set the quality slider to +2, rather than -1.

As usual, having lots of creative control means dealing with lots of controls, so a lot of 'tweak/quick render/look/tweak again' is involved. Not good for deadlines. Glad i'm a 'hobbyist'!

I  usually set up a 'User' render to render a small selected area to the screen at pretty high pix dimensions, in under 1 minute, for faster tweaking. 

Sorry i can't give more exact settings advice, but you know how subjective these things are, and i can't see the results from here, lol. 

HTH