A few years ago (almost to the day), I was taking a social dance class. We were preparing to perform a mambo for a university function and so we had dance partners assigned, as opposed to our usual pattern of rotating every few minutes. My partner (her name is Michelle) was fun to dance with and talk with. She also happened to be gorgeous - and she seemed interested.
But social dance classes make asking out a little difficult. As a rule, I don't ask girls out in front of other people. It has less to do with the fact that I might get shut down in front of others and more to do with the fact that she's likely to be uncomfortable with it (yes, I plan to propose in private). Since everyone leaves class at the same time, it can be a little difficult to catch someone and ask her out - especially if you go in different directions.