My third language is better than I thought!
I was at a ballet and the only words were in a Spanish song, which I actually understood! I didn't even see myself as able to have a conversation in Spanish properly!
That'd be amazing! I am going to start looking for one now!
Carmen is in French, and is a fairly popular opera, so you should be able to find a showing without too much trouble.
As far as others... http://en.wikipedia.org/wiki/Category:French-language_operas