classical ballet solo?

[Rain]

I'm looking for a song to do my senior ballet piece to. I prefer it to be the typical, classical standard...it doesn't HAVE to be from a specific ballet, but I have to be able to dance to it. I would prefer an adagio (perhaps a pas de deux...) but like I said, doesn't have to be. It needs to have some variation to it though, as it is a solo and I want it to be interesting (of course!) I feel like classical ballet is being replaced by contemporary, which is why it absolutely has to be classical. Any ballet dancers that have done solos and used slow, classical music OR people that have any ideas? thanks!