In reply to MG:
> Free-trade, ...
Doesn't need the EU, indeed the EU is a hinderance to proper world-wide free trade, since their insistence on the CAP and on subsidising their agriculture has stalled the Doha round.
> free movement of people, ...
Doesn't need an EU, you can make whatever visa rules you like (as shown by the fact that Switzerland participates in free-movement rules).
> political stability, peace ...
Looking at Greece, I don't see that the EU and the Euro have produced political stability. And I don't agree that peace is caused by the EU.
> joint planning on major projects, ...
Things like CERN, ESA etc work fine without being EU institutions.
> clout in trade negotiations ...
Not so good if they use it against what you want.
> joint approaches to big challenges, ...
That's very vague.
> ... cultural interaction...
Which of course could not possibly happen without the EU.
> , imagine how that would multiply with n countries forming bilateral agreements.
Treaties do not have to be bilateral! The CERN and ESA treaties are not, GATT is not, etc, etc! The alternative to the EU is *not* bilateral treaties only.
> The only comparably successful area in the world is the USA, which is similarly integrated.
It's notable how you only count something as "successful" if it is big and integrated. In what way is Canada unsuccessful at the moment?