My two cents:
View by genre with sub-genres:
$if(%genre%,$left(%genre%,$sub($strchr(%genre%,','),1))|%genre%,--- Undefined ---)|$nodisplay{$if(%album%,$if($stricmp(%album artist%,%PUBLISHER%),-C,%album artist%$if2(%RELEASE_DATE%,%date%),-S))}$if(%album%,$if(%album artist%,$if($stricmp(%album artist%,%PUBLISHER%),--- Compilations ---|,)%album artist% $colour{--}$if(%RELEASE_DATE%,'('%RELEASE_DATE%') : ',$if(%date%,'('%date%') : ', : ))$colour{}$if2(%album%,%directoryname%),$colour{--}%directoryname%)|$if(%tracknumber%,$colour{--}%tracknumber%. $colour{}[%track artist% -- ]%title%,$if(%title%,[%track artist% -- ]%title%,%filename%)),--- Singles ---|$if(%artist%,[%artist% -- ]$nodisplay{%tracknumber%}%title%,%filename%))
Update:
- Items with no %album% are sort as "--- Singles ---"
- Items with %album artist% == %PUBLISHER% are sort as "--- Compilations ---"