I don't know what things I might have heard it in, it was an especially sad portion, in a sad scene. My brain is saying I heard it in an episode of Cowboy Bebop, but I'm not 100% sure.
But I figured the veteran music fans might know. It's called Suite Bergamasque Clair de Lune.
I love Clair de Lune. <3
They use it in a LOT of stuff. The Christmas Cottage and Twilight were the first ones I could think of (although I didn't like either movie)