This is the first year I have not had the D700 and shot with the D90 instead. For this type of photography, the D700 is a far superior tool. Better metering, MUCH less noise, faster autofocus and generally faster to respond. I found that I needed to use ISO 3200, and this created significant noise in most scenes, whereas the D700 would have had almost none.
As for lenses, I shot the portraits and wide angle stage shots with the 18-200mm, which worked out OK, and most of the play with the 80-200mm f2.8. This lens is a bit too long for stage photography on a DX camera, especially at 80mm, but 200mm does allow some great upper body portraits. The 35mm f2 and 85mm f1.8 weren't used at all, apart from a brief try out.
The 18-200mm wasn't any good for the stage shots as the slow shutter speed blurred people if they moved, though the VR did keep shake in check.
Conclusion: Only use full frame for stage shoots.