Depends what you are comfortable in. I have seen them all - from tux to Dockers and from gown to tights. Usually people at orchestra floor is more dressed up than balcony.
Elegant casual to casual
Wear something nice. The degree of formality depends on the performance and what you feel like! On a Saturday night premiere you'll see slightly more formal clothes there, but Sunday matinee and weekday night performances are more casual than I would've thought. I've worn a suit with the tie ubdone and I've also worn dark jeans and a collared shirt. Women often wear nice pants, a skirt, or a dress. There's no dress code exactly, but if you want to feel like you belong there then at least some nice pants, a collared shirt or a blouse, and just about any shoes but sneakers. Heels or flats are totally fine and for men leather. Hope that helps! And remember that you can always dress for the experience you want to have. If that's a floor length dress or a tux then that's fine!
Thanks all of you for your answer.
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