Quote Originally Posted by Throbert McGee View Post
For example, if I'm not mistaken, the noun аэропорт was historically considered an "open space" (think of the runways) and therefore usually took на, but nowadays the word is seen more as an "enclosed space" (think of the terminal buildings) and thus the preposition в is often preferred.
No, "в аэропорт" and "в порт" only possible both in the past and now.

Quote Originally Posted by Demonic_Duck View Post
Another example: «в России» = in Russia, but «на Украине» = in Ukraine (note that Ukraine is the exception to the rule here, almost all other countries use «в»).
"На" is used with islands (на Кубу, на Таити) and with many Russian and Ukrainian provinces and historical regions (на Брянщину, на Волынь) so the argument is: as Ukraine in not a province any more but a separate state, it should be grammatically supported.