My Favorite Settings
I always shoot with ADR at NORMAL on the D3 and D300, or AUTO on the D700 and D90. This eliminates the ability to control the brightness (gamma) and contrast settings, since they are optimized automatically by the ADR system.
For Things
I set the sharpening to 5.
For photos of things, I usually start at VIVID and crank the saturation all the way up to +3. This gives me the psychedelic look I love.
For Accurate Product Colors in the Studio
I use STANDARD.
I prefer sharpenng set to 5.
I honestly have no idea if Nikon's ADR can work with studio strobes, so I turn it off and set contrast down to -1.
For People
For photos of people, I use NEUTRAL and set the saturation to +1. I prefer sharpenng set to 5.
STANDARD is less wild then VIVID, and NEUTRAL has even lower contrast.
You may prefer STANDARD and +1 or +2 Saturation.
Play with this: we all will prefer something different.
If I'm outdoors in direct sunlight light, I often also have to change exposure compensation between 0 in NEUTRAL, and to -0.7 in the contrastier VIVID and +3 saturation setting. Nikon's Matrix meter still isn't smart enough to read the effects of Picture Control settings, nor do the saved Picture Controls recall the compensation settings; that will have to wait for newer cameras.