a functional opener could be anything! i could try and give you some more, but, your are the best to know which question is relevant to ask her. just ask anything!
if not a functional opener, use a spontaneous, like: "the clarinets had a really off day today hu?"
or "where did you get this shirt?! my mom has the exact same one!"
the best spontaneous openers are the ones that occur spontaneously
so.. open you eyes.
now listen, you are part of the same social circle. You don't have to come up with a really good opener to open a conversation.. just open with anything.. you already have things in common.
about the opinion opener, it would definitely work, but you have to have a good reason for asking. it would be weird to walk up to a random person within 60, and ask her specifically something unless you say something like "i wanna see what an oboist will say about this:" (if she's an oboist )
or even "you seem more down to earth then most people here, what do you think about our friend tom.. bla bla bla"
in a club\bar situation you will have to have a very tight routine.. here, it would be much much easier so... just give any reason and start talking.