Sean,
Thank you for the link to the thread. I scrolled to the end of the thread and found Sam's summary, which provides great advice for achieving good balanced fill-flash results.
I thought I'd add one additional consideration. Although "Auto" white balance works well in many situations (and gives you an additional option to select if you are using Nikon software), I've found that many times I am happier with the "daylight" white balance setting. Its easy enough to shoot the image on "auto" and then have the "daylight" option as a backup in the event the auto setting doesn't result in a pleasing image. Often our eyes (our brains, really) expect to see some color shift in certain scenes. A scene that is too "neutral" will tend to look odd.
By the way, what software do you use for post-processing your images? Do you use Capture NX?
Keith