i think most of the time genre only makes sense with music that is a bit older. so that is bebop, or post bop. and only for part of the songs, becuase so many fall between genres. and a lot of genres live shorter than the music. some genres are there always but they get another meaning and some genres just don't make sense, worldmusic anyone
. so i think there are more ways to tackle this. one thing is to remember that genre is not music. just a way to catalogue it. so catalogue it in a way that makes sense for your library. when you own a lot of jazz from different periods it makes sense to split that up in post bop, hard bop freejazz etc. but when you love pop and rock, i guess jazz will do just like worldmusic instead of fado, oriental dub, etc.
indeed, joni mitchell, a singer/songwriter who plays music that could be considered folk, or pop, or jazz.
i recently stumbled over the genre 'freak folk' for joanna newsom. sounded too cool to ignore. wonder who is in the same genre.
gab