Well, first someone needs to put together a very good background, either you or the prom committee. Try to be sure that they give you enough depth to get back a bit and to set your lights so that you don't have to use a wide angle.
Some form of studio lighting would be the best because of the modeling lights and the quick recycle time. Something like ABs would work very well.
But if you have to use your SB600 and SB800 you could trigger them from the D200. Be sure to rotate the base of the flash units so that the sensor (on the battery side) is toward the camera. Be sure to test it in a similar room, in advance, to be sure that the built-in flash will trigger the remotes. If the room is very dark you may have problems.
Since you will be shooting couples I would use two lights bounced off umbrellas (or some other form of diffusion). Put one at about 45 degrees to the side as the main light and the other near the camera for fill, turned down to about 1/3 the output of the main light. Experiment a bit to be sure that you get the ratio you want.
The biggest problem with using SB600/SB800s is that you will end up shooting at about f5.6, even at ISO 400. With some form of studio lighting you can easily shoot at f8, or even f11, and get better results.
Hope this helps a bit. Good luck.
--
JohnE
Equipment list in profile