Answering my own question, I was about to claim that my first non-American musical, seen onstage, was Evita. Der Brucer took me to see it, as produced by the Long Beach Civic Light Opera, within weeks after we first met. My complaint was that it hewed too closely to the Hal Prince production, and that there were probably other ways of presenting the show on-stage. (This came from my original familiarity with the show from the original concept album, starring Julie Covington.)
But, I've had to reconsider this answer. There was a major trio of musicals that I saw at Fresno State, when I was a student there: Stop The World..., Oliver!, and The Threepenny Opera.
The problem with Stop the World... is that you have to have a damn good Littlechap, or the whole enterprise falls flat. What I saw was one guy on stage, sorta all right, surrounded by lovely women in the chorus, who got to do very little since the show was all about Littlechap. The writing of the show worked (and it was a damn good concept musical, a decade before the concept musical became accepted by the press as the new way to do musicals), but the acting I saw was not quite there.
Oliver! was good, but hard for a college drama department to pull off, mainly because of the large troupe of young boys required. I suppose they could have done the show with fraternity pledges as the orphans, but that would have been a little too inside, and over the heads for most frat brats.
Threepenny Opera is the most classic show of the three, I feel. And Fresno State gave it a good production. The only real flaw was the lighting, of all things, as I've since read that Brecht liked to use flat, bright white lighting, and this production's lighting designer was trying very hard to get a good grade, showing all his skills in different lighting techniques, and gelled the show all over the place. Other than that, everything in the show was very true, and very well done.