In a lot of songs, just singing, "La, la, la, la, la," would be seen as a cop-out for not writing actual lyrics or as a guide vocal to suggest where lyrics should go in the finished product.
That's not the case, however, in Chicago's "Happy 'Cause I'm Going Home." Decades after first hearing it, it still enters my mind frequently. The tune's rhythm and instrumentation are compelling enough to sustain periodic "La, la, la, la, la" intervals--and the "La, la, la, la, la"s are catchy, no matter how often how you hear them.
This is an underrated example of Chicago's strength as a band. Even if the song isn't to your taste, I don't see how a listener couldn't respect the musicianship of every player on this track.
