1. Use beets to move my music into folders based on file type
2. Use xld to convert the FLAC files to AAC, which will write the proper iTunes tags for gapless playback
3. Drag songs into iTunes.
4. Sync iPod
5. Relax and enjoy music.
foobar2000 can do so, but you have to configure a column for it.
Also beware that more recent versions have an annoying remapping to %albumartistsortorder% - for lossies, but not for Vorbis comments.
Ok, here is the full explanation