Yes be prepared even though SF can be known for its fashion, it is rarely seen. Wear whatever you are comfortable in and what you feel like. For me I find it disappointing but no one seems to dress up anymore including NYC. except maybe the MET. Have fun
People wear everything from Levi's and tennies to designer gowns. It's an old theater (seats are small, aisles narrow) so dress comfortably but it IS an opportunity to really spiff up if you're in the mood.
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