You should check out the Comic-con Convention that happens in San Diego every year.
Here are images from the Comic-Con in San Diego: http://www.google.com/search?hl=en&client=safa...
This is a HUGE event in the San Diego area--
People from all over the world come to this each year.
You can barely even go out to a restaurant or bar this week (in the downtown area) because there are so many tourists in town for this).
I would follow their formula.
This has been HUGELY Successful in San Diego.
If you found an equally attractive city that has a wonderful convention hall and other tourist-y type things to do while people were in town, you could have a similar success--- particularly if you were able to find the people who rent booths and exhibit spaces at the Comic-con Convention.
They have built the prototype.
All you would have to do-- would be to find an equally attractive city, convention hall, and find their contacts by attending one of the Comic-con Conventions yourself-- and meet the people who are exhibiting in this one!