I still hate the idea of being restricted to rules like this as I prefer to play my games just as I want them. But if it's no possibility at all for it to change I would like to at least propose a minor change. You guys should skip the focus on countries and instead divide the world into continents or sub-continents. The idea you had in the first message are way too much focused on certain larger countries. An example could be something like this.
WESTERN EUROPE (All of Europe except the former Soviet Union)
International: Berlin, Paris, London, Madrid & Rome.
National: Stockholm, Copenhagen, Barcelona, Amsterdam, Munich, Dublin, Belgrade, Athens, Lisbon, Vienna, Prague, Oslo, Helsinki, Reykjavik, Manchester, Brussels, Zurich, Milano, Zagreb, Marseille
EASTERN EUROPE (Simply the former Soviet Union*)
International: Moscow, Warsaw
National: St.Petersburg, Novosibirsk, Krakow, Kiev, Riga, Tallinn, Bucharest, Astana
International: Tehran, Tel Aviv, Istanbul, Riyadh, Dubai
National: Baghdad, Beirut, Doha, Amman, Jerusalem, Damascus
International: Tokyo, Beijing, New Delhi, Bangkok, Hong Kong
National: Shanghai, Osaka, Seoul, Mumbai, Chennai, Taipei, Singapore, Hanoi, Manila, Kuala Lumpur, Dhaka, Islamabad, Karachi, Colombo, Jakarta
International: Sydney, Wellington
National: Perth, Brisbane, Auckland, Hobart, Darwin
International: New York, Los Angeles, Miami, Toronto, Mexico City
National: Chicago, Atlanta, Dallas, Seattle, San Francisco, Anchorage, Denver, New Orleans, Honolulu, Vancouver, Quebec, Guadalajara
International: Rio de Janeiro, Buenos Aires, Caracas
National: Sao Paulo, Montevideo, Santiago, Bogota, Lima, Guatemala City, Havana, Panama, Quito, Asuncion, Santa Cruz, Fortaleza
International: Cairo, Johannesburg, Lagos
National: Cape Town, Algiers, Addis Ababa, Dar Es Salaam, Dakar, Accra, Antananarivo, Abidjan, Casablanca, Nairobi, Luanda, Tunis
If I counted this right this is 120 airports. 30 International and 90 national. This is a little more than the 80 you where counting on but not much and it would add very much to the diversity of the game.
Just think about it. With the initial system you would have to exclude some major airports, mainly in Europe. For example Amsterdam or Brussels are important cities but in small countries. And Venezuela? Which other major cities do we have there except for Caracas?
And as I said in an earlier message. As this system is unrealistic in the first place, Berlin should be the major Airport in Germany and not Frankfurt. Otherwise you would have to make maybe Atlanta as the major American airport to be consequent.* Except Prague which are so close to Western Europe both geographically and cultural that it would be silly to not include it as Western.