First, Van Halen is mostly a pop group with heavy metal as their 
enabling form (discuss).
And I would add that Jamie's Crying (is it "Cryin'" with no g?) has a 
very pop chorus.
If you haven't already, read Chuck Klosterman's  Fargo Rock City,  in 
it he makes the case for 80's hair metal and stuff like Van Halen. 
He draws particular attention to the layered backing vocals in Van 
Halen, which, if I got it right, were all done by the bass player 
Michael Anthony (yes, he of the Jack Daniels bottle shaped bass). 
Huge stacked harmonies abound in all Van Halen choruses, which are 
kind of an obvious overdub for the four piece.