I think you may be multiplying your lights too early. I used several lights in most of my renders, but the basic lighting scheme I get done with very, very few items. Think of this as two separate areas; first, you are trying to light the entire scene. For that, use very, very few lights (I've lit a scene with nothing but sky dome) and tweak the settings. GI, and soft shadows, can be a great help in getting smooth coverage and a pleasing basic light. ON TOP of that comes "specials"; little spots that liven up the pic. This might be just to bring a little more focus on a character's face, or it might be to add a little light coming from some object in the scene (a candle, monitor, whatever). I tend to run GI at values from 60% (more of a fill) to 140% (more of an independent light). In one pic I did the skylight was masked off by scenery and treated as the "key" light in the scene, with bounce of that scenery treated as the "fill" light for that scene. Skylight, I've found often needs to be cranked to 200% or more...but then, I love the look of a cloudy or overcast sky. (A note on terminology; I am a theatrical lighting designer and I tend to think in those terms -- and use terms from that field -- when I do lighting in 3d. Also, as a theater lighting person I tend to think in terms of the story-telling potential of the light; that it is responsible for describing much about the scene from time of day to mood. And it perhaps goes without saying that I default to the dramatic!) A last thought that might be intriguing to you. My last render, I rendered one light at a time and comped the results in PhotoShop (using G-buffers for control). It saved a lot of the usual time in tweak-render-tweak-render, moving it to PhotoShop where tweaking the relative levels was much, much faster.