Are you talking about vendors traveling or customers? If you are asking about customers, I have no idea. As for vendors, they come from across the country to be here.
As for helicopters, the ones that have been there in the past have been Hirobo, Thunder Tiger, Kyosho (via Great Planes), Vario and Kalt whn thy were with Airtronics. Since Kalt is out of business and who really cares about the Nexus, that pretty much leaves Hirobo, Thunder Tiger and Vario. To be fair, I have seen some Picollo's and Eco's there, but they were from retailers, not manufactures.
If you want to take a look at the past few years AMA shows in Pasadena, go to the very top of the Run Ryder page and click on "CONTENT." Then scrool down to the AMA show links.