Recommendations for what's appropriate? Suit and tie for men? How fancy for women? Whatever it is will have to be small and compact! Thanks.
At most classical music performances I have attended in Europe (excluding the Mozart and Vivaldi concerts that only tourists go to), the dress ranged from formal wear to dress casual to a few students wearing whatever they pleased. The tendency, though, is more towards shirts, ties and jackets for men, and evening dresses for women. But unless you're not wearing anything (or don't have a ticket), you won't get turned away because of what you wear.
We went to a performance by a Dutch dance company there a few years ago and I felt way over dressed in a coat and tie. Most of the audience was young and either in full Goth mode or jeans. I only saw a few other guys with ties. That may or not be typical for that hall.
The performance was very cool by the way. It actually rained on stage in one piece!
For small, compact, appropriate, and wrinkleproof, you can't beat a black dress in that matte jersey material. You can dress it up or down, smash it into your suitcase, wash it in your hotel sink, and hang it to dry overnight. Magellan's, Travelsmith, and Chico's usually sell some version of this type of dress.
I have seen performances at the Opera Garnier. No need for a suit/tie for men -- a nice sport jacket is fine, with a collared shirt. Black dress and nice shoes for women is always appropriate in Paris. Doesn't have to be fancy, though. Have a wonderful time!
When I went to the ballet at the Opéra Garnier in July 07, I wore my black Chicos travelers dress pants, matching top and my black light rain coat - it was cool and wet when I was there. I love the Chicos clothing, light and wrinkle-free right out of the suitcase.
I saw men dressed in suits and ties and women in fancy evening gowns, but there were also students (I assume) wearing blue jeans - very stylish, but still blue jeans.
Enjoy - I love the Chagall ceiling!
We went to opening night of a ballet there about 3 weeks ago and were concerned what to wear as well. we wore cocktail dresses and saw everything from what we had on to jeans, dress pants and jackets for women, etc. You will truly be fine in whatever you wear-have fun. It is a beautiful place.