Having not been to Nationals since 2002, I have yet to see the city format. But, I do think that the city that holds it needs the following criteria:
-Temperate climate. With an activity that requires so much outdoor work, it makes much more sense to be in a place that will have little finicky weather.
-Space. We're a decent conference size, and because of that we need to look at cities that are available and can handle our size in conference area as well as hotels. Even better would be to go to a place that has more than enough room to accomodate us so that a bidding war might start.
-Travel Costs. I also feel that it should also be decided by the area where the majority of the teams for them to travel to. We've had selective Championships now for long enough that a rough estimate can be made as to where the majority of teams are coming from to compete (especially the repeat visitors). If the minority of the people are coming from the west, then getting a place that's cheapest for them to travel to is key for strengthening that area.
That said, FIRST also needs to think of itself and how it will shuttle its employees there, since they are the ones handling the event. Doing a quick Orbitz search, it was significantly cheaper to fly to Orlando from Manch-vegas than it was to Houston or Atlanta.
-Support. The city and FIRST need to be excited to be together to make the best Championship they can, and it needs to be an area where ample volunteer support is available (seeing as that has been a problem in the past).
As for a specific city, that's not my call.
