Well...from watching the show recently, it seems like a larger percentage of contestants are from Los Angeles or the surrounding area. Now I'm thinking that they're trying to keep interest in the show up in other parts of the country. Economics may play a part, too. If you're worried about making rent/mortgage or a car payment, you aren't going to shell out a couple hundred bucks just to wait in line for a TV show. You may drive half an hour to an hour to go to a contestant call, though. I imagine that this will be a fairly big deal in the five chosen cities. Lots of press coverage. Local news, at least from the CBS affiliates. Maybe some articles in the newspapers. Could be a good thing.
So do we know if they'll be flying to each city? With five cities announced, and more to come, I'd imagine it'd just be a TPIR version of the Wheelmobile/Brain Bus.