I would try native first (which should be around 5000 k... 6500 is too cold, however not all LCD:s can handle 5000 k. My experience with NEC displays is that most of them can handle it. I run mine (2180 SpectraView at native).
I use Spectraview II and a target of 6500k, but since Spectraview II is completely automated I am not sure what it is doing internally to hit the target.
To clarify my previous post. 5000 k only applies if your output is print (as in magazines and newspapers). If your output is web/screen, then the colder settings might be better suited, since thatīs what most uncalibrated monitors are set at.