regarding the longevity of theme songs:

My son plays in a jazz band. Several of the songs that are most enthusiastically received by the audience at every gig are theme songs from movies and TV shows.

I've been at gigs where there was very little audience interaction going on until the band played a theme song (The Jeffersons, The Pink Panther, etc) and the room filled up instantly with people who were singing along!

STRONG audience identification! And it seems to be predictable and consistent.