I went to the Classic Gaming Expo a few years ago when they used to hold it in Las Vegas. While it was pretty cool, there were hardly any TG-16 games at all. In fact, I think the only Turbo/NEC stuff that I found was at the Telegames booth. Other than that, there was tons of Atari, Coleco, and Arcade stuff there. The hall was lined with arcade games that were all on free play. Again, it was a very cool event, but I don't recommend going there solely for NEC stuff as you probably won't find much.
Oh, and don't forget about the Midwest Gaming Classic:
www.midwestgamingclassic.com.
They don't have this year's dates posted yet, but I think it's sometime this summer in Milwaukee.
And I would be more than happy to attend an NEC only gathering, provided there would be a lot of stuff to see/buy/play.