As a ballet accompanist, I am always trying to expand my repertoire so the dancers don't hear my same pieces over and over. I've found that every instructor wants something different. Some prefer more classical, some prefer music from actual ballets, but most don't care what I play as long as it fits the rhythm and feel for the combination.
One thing I enjoy doing, is taking a song I've known for years, and discovering it can have a "ballet make-over" and sound completely new. This song was like that. Because of the chord progressions, square phrasing, and 3/4 time signature, it made a perfect adagio when I slowed it way down and added some languid arpeggios. Like most of my improvisation, the result seems to be the love child of a dark, angry Russian, and Honky-tonk music. See if you can hear what song it is. I play the familiar melody about a third of the way through...
I'm sure most of you will get it, but just in case, I'll post the answer tomorrow, as well as any guesses below in the comments. :)
You might also enjoy this video as well, where "Hotel California" becomes an intense, slow waltz: