I think mine would have to be a double CD set. I listen to a lot of music, and my moods are often changing, so this would need to be represented appropriately.
One of the tracks on mine would be "Lovers in a Dangerous Time". Not because I am one, just because I listen to it so often, and it always inspires some kind of emotion in me. I'd have slow-moving instrumentals, and fast-paced rock songs, and ooh, ooh, "Ballroom Blitz". I think I'd even need a song on there which I hate, like "As Tears Go By".
You know, I'm starting to think I'd need a whole collection. Similar to "the best of the 70s" or "90s love songs", only with, you know, decent music.