this is very interesting, packed with poll data about how safe new yorkers feel:

http://www.nytimes.com/2004/08/27/politics/campaign/27york.html

Some New Yorkers said they were planning to be out of town during the convention: Eighteen percent of Manhattanites polled and 13 percent of people citywide said they were expecting to be gone. It was unclear how many would have done so without the convention. Others said in interviews that they worried about the expense of the convention, the disruption, the anxiety.