When we did it we used a band called "dead can dance" is awsome gothic orchesteral music. we used a cd of thers called Labyrinth check it out its perfect.
Or take the audience in the opposite direction for contrast and use period music. While I can't suggest any specific tunes, consider traditional colonial American tunes and/or (protestant) hymns (on piano or other traditional instruments). Or consider English folk music or Scottish folk music.
(You can probably find the music at Borders and even listen to samples of the songs off the CDs before buying anything.)
when we did the show we never put any thought into this until opening night right before the house opened, so we ended up with blue man group. it worked allright but wasnt the greatest