I have had great and not so great experiences at both. Service has been fabulous at both every time we have went, both of these know service and have mastered it.
The CG has a more adventurous menu, changes more frequently, reflecting the seasons. It also, as others have mentioned, has a more bustling atmosphere.
Narc. menu has very mild changes. I find it to be a good choice for people with less adventurous palettes. The atmosphere is much more shhhhhhh than CG in my opinion.
I have had great and not so great food at both. Both have unique views of the MK fireworks. As someone else suggested have evryone look at the menus online and put it to a vote. I think you would enjoy either.