Although my favorite group is Journey, I'd have to say my favorite song of all time is "Every Little Thing She Does is Magic" by the Police.  Sting has an awesome voice, and I love the idea that a man would be so in love with a woman that everything "she does is magic."

Oh, my. I have so many favorite songs, and they range across many genres as well. I don't think I could ever narrow it to just one, but I thought about your question from the point of view of being stranded on a desert island with a very limited list on my ipod, and that helped to focus it.

I would want to have Aaron Copland's "Appalachian Spring", along with selections by Beethoven ( Fifth and Ninth Symphonies, Eroica, Moonlight Sonata) Bach (Art of the Fugue), and Vivaldi (Four Seasons).

I'd want some Scott Joplin rags, and some Gershwin, and Count Basie.

On the modern side, there would have to be Pink Floyd - the Dark Side album (especially Great Gig in the Sky, which I could listen to all day), and Meddle. Something from Rick Wakeman - the King Arthur album, or Six Wives of Henry the Eighth. Also some Yes - probably the Yessongs album. And the Moody Blues are a must.

I second #4.  I like Enya.  I would like to recommend an app called SoundHound. I have it on my iPhone, but I am sure you can get it on most smart phones.  You can hold your phone up to any music and it will tell you what it is, and you can buy the song right then!  So often I hear a song on the radio or tv and I like it, but have no idea what it is.  This app helps me find new favorite songs all the time.