Andy,
Really depends on your definition of city, and East. The only strict dictatorship left is Belarus (not that I'm pretending Russia is a model democracy). IST (as in Ataturk) is on the European side, metro Istanbul is 13m, counting both sides, the European being larger. We would assume MOL would go for SAW, which is on the Asian side, but recent form (and Jet2) have shown no reason to take that, or FR going into Turkey at all, as a given.
AMS serves a massive hinterland - the whole Randstad is some 7m, and that includes Rotterdam, which is 26m from AMS via FYRA, about the same time the bus takes from RTM to Centraal.
The Rhine-Ruhr 'Essendorf' connurbation could be measured as up to 10m, although FR do server NRN, aka Dusseldorf West.