AndDontCallMeShirley -
Another pattern may reveal itself when you look at the international convention city choices. (Please don't find me as a racist or being guilty of profiling - it's just an observation)
Detroit, Atlanta, New Orleans, Indianapolis and Landover, MD (Washington DC) all have a significant population of African Americans. Working class. Middle to lower income brackets.
Looking at the other cities chosen for international conventions - Rutherford, NJ & Arlington, TX (Dallas/Ft Worth) - it may be that these were chosen because of the very large numbers of Hispanic persons in these areas. Texas goes without saying. While Rutherford, NJ has a nostalgic history with the Society, it is also in the center of two towns with significant Hispanic populations - Patterson and Elizabeth. Again - working class and middle to lower income brackets.
These racial and economic "groups" are the target of the Org. They need these people.
Of course Hawaii has to have an international convention - awesome vacation for the Org. big shots.
And Seattle is necessary - the last major stronghold of the International Bible Students in the States.
ginger