I shoot a D7000 and an X-E1. I find the "flattest" jpg look for Fuji is "Pro Neg Soft." You would probably have to make some additional adjustments to achieve the true Nikon "Flat" look. Those adjustments would probably be in the direction of less saturation and less contrast. The idea being that color saturation and contrast can always be added in post - shooting with the film simulations can clip the individual color channels - you can't get that data back. And if the camera blew the WB setting, you're really hosed. Shooting RAW avoids all this, but I know that's not your thing.
Long story short: try Pro Neg Soft. "Ns" in the quick menu.
