I'm playing harp this Sunday evening for a kind of advent labyrinth walk at the UU church. This means I've been practicing a lot, since I have to provide about a half-hour's worth of music while people walk a labyrinth of evergreen boughs and light candles. It's times like this when I realize that all of the music I know (or at least can play on the harp) is divided into two groups: music that has a C-F-G-C chord progression and music that has an Aminor-C-G chord progression.
I think the only exceptions are "We Three Kings" and "Diamonds Are Forever."
Anyway, I have to make a play list so that there aren't too many lurches in song style.