I've done the same and have found that the S100 doesn't really add all that much to NXT. I have also found tha S100 is not very durable. It sure looks good though.
I usually use do two applications to NXT to my black Hemi and my black Harleys and they all look great.
This afternoon, I'm going to try ColorX on the Hemi. It is supposed to have some carnauba in it. A one-step with "pop" is what I'm really looking for.
Wipe a panel on, wipe the panel off. You can let it haze over the whole car if you want to, but theres no need to, and going panel by panel is probably easier.