Re: Irish passport
"we could go to the Netherlands or Spain, where it is recognised and then I, as the spouse of an Irish passport holder, could get Dutch or Spanish citizenship, and given our jobs, that would be great. So father-in-law is being encouraged quite strenuously."
I'd be careful about this. Usually a marriage is recognised or not by all countries involved. If in the passport issuing country you are not married, then you can't transfer it over.
Not sure about Spain, but for the Netherlands (since I"m looking at that now) to get nationality you need to be married to a Dutch national, or to have lived here for 5+ years and give up your current nationalities. Oh, and have B2 level Dutch, whatever path. So unless your missus is Dutch, I'd suggest something else.
The first step would be to get *properly* married (to whatever standard the Irish require) after your wife has her Irish passport, then apply for an Irish passport.
If you're eligible for Spanish or Dutch nationality directly, then apply directly :)