The only concrete example of min (add9) chords in popular music that I could find was Every Breath You Take by The Police. It’s usually far easier to grab a min9 chord on the guitar, but the the add9 version has its own sound and actually seems to convey more tension to my ear. It’s also a good chord to get the fingers used to less familiar locations on the fretboard without making any extreme stretches.
Maj (add9) Chords
Major Add 9’s are great chords without being overly complex. The triad on strings 2/3/4 plus the 9 on the top string is a personal favorite, as is the movable form of the open C (add9). The root-3 version is really more of an inverted Mu (1/2/3/5) chord which I’ll dig into later.