So... you want an example, barring all the examples that work? I've really got no idea what you're asking for here. You asked for an example of multiculturalism working - I provided it. The only difference between the places I named and the places you named are the fact that, yes, the places I named have a much better reason to be open to multicultural societies than other places.
Well.. I was asking half-rhetorically. I am sceptical of multiculturalism (as I am generally sceptical of the human ability to co-exist peacefully). I think that what most people cite as examples of multiculturalism are not really examples that work on a larger scale. Of course you can have a multicultural workplace. But you are probably all using the same language and there is only so much cultural conflict that can arise on a workplace. A city can be multicultural, but in my experience there usually is some kind of segregation, where most minorities have their own quarters.
IMHO a society consisting of people with immigrant backgrounds is not really multicultural, as there is a main culture into which all people assimilate more or less.
Integration is handled quite differently in the US anyway, there is no social security, so immigrants have to learn the language and find a job. In fact legal immigrants to the US are often highly qualified. In Europe, immigrants are often poorly educated, are elligible to welfare benefits and thus under much less pressure to assimilate into the main culture. This leads to all sorts of problems, like 3rd generation immigrants not being able to speak the language of the country they live in, and because of that struggling with education and finding work.
Assimilation is in an european context often seen as the opposite of multiculturalism, and is frowned upon by parts of society, most notably leftist politicians who think that assimilation is nationalist and immigrants themselves (often coming from highly nationalist countries), who don't want to give up their cultural/national identity.