I use the a custom tag, "Style", in my library so that tracks like ·Ella Fitzgerald and her Savoy 8 - Shine (1936)· can have,
<Genre>:Jazz
<Style>:Early Jazz;Vocal Jazz
and ·Glenn Miller and his Orchestra - Chattanooga Choo Choo (1941),
<Genre>:Jazz
<Style>:Big Band;Traditional Pop;Vocal
while ·Dave Pike - Jet Set (1966) has
<Genre>:Jazz
<Style>:Smooth Jazz;Instrumental
so I can either search for "Vocal" or "Instrumental" and work from there.
One of these days I'm going to move all my Genre tags to Genre Category and then all my Style tags to Genre tags and do away with the custom tag. Yeah. One of these days......