Originally Posted by
HkCaGu
I'm assuming you'll be in Iceland for a significant amount of time, while time in Switzerland and Finland is insignificant. So Iceland is where you should submit her visa application. You should do research where it would be easiest to apply, in Asia, Ireland, or the US. (Beside the embassy/consulate availability issues, China, for example, makes it hard to apply from a country where you're not residing.)
It should indeed be an Icelandic visa when Iceland is the main destination or the Schengen country of entry on a trip (or series of trips) where there is no primary Schengen country destination.
Most of my Chinese visas in my US passports were issued in countries in which I was not resident at the time of applying; and it was always same-day or next-day pick-up. That said, some countries (or some embassies/consulates) in some countries can indeed make it difficult for non-residents to procure a visa.