The problem, though, is that the major shows that thrive in Vegas focus on big-dollar merchandise in absolutely HUGE industries: consumer electronics, computer software and computer/console video gaming.
I have been going to the CES (Consumer Electronics Show) in Vegas for years now, every January. That is one helluva show -- it has to be seen to be believed if you've never before been. It flourishes because the people who buy and sell this stuff are full of money, and not afraid to spend it. What's a week's stay in Vegas when you're talking about dropping twenty grand on a home theater system?
Although I'm not saying that such a show for R/C would fail, I think it would be harder than people think to attract R/C consumers out there. Still, I think R/C needs two shows: a trade show (think Hobby Expo) and a consumer show (like this one in Vegas, or the RCX one in LA). I don't know if it can handle a third.