I only really have one go-to voicing of this chord, the 5th-string-root version. That one isn’t overly muddy or difficult to grab and feels similar to a 6 or a 6/9 voicing.
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.
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.
This one is quite uncommon in rock or pop but easy to find in jazz where it’s usually used as a more interesting tonic chord. The only obvious place I could find this in the rock world was America’s Horse With no Name where the second chord of the main vamp is a 6/9. Interestingly, this chord contains the entire major pentatonic scale and is also a set of stacked fourth intervals, meaning you can play a whole barred figure at any fret and technically be playing a 6/9 chord with the root on the third string. I’d think you’d want a strong bass note behind the guitar to make that work. I haven’t tried it, but I thought it was interesting enough to include.
To be fair, I mostly threw this one in for the sake of completeness. I won’t claim I’ve had much success with the min6, though I did enjoy the root-5 variation that looks like an ‘M,’ as it is easily dropped to a minor add-b13 chord that I’d never played before. I also found that this chord works much better for me in arpeggio form. Sounding the notes individually scales the heavy dissonance back to a more usable tension, a strategy I plan to test further in other chords I’ve had trouble using.
The major sixth is another chord that feels more jazz than rock or pop, but you don’t have to look too hard to find it in use. Lenny by Stevie Ray Vaughn and Sun King by The Beatles are the best two rock/blues examples of a major 6th chord that I came across.
Another chord that isn’t the easiest to use in a rock context but shows up frequently in jazz. Also referred to as the half-diminished.
Lots of overlap here with sus2 chords and easy to confuse the two sonically without resolution back to a major or minor. I personally overuse the two barre forms and don’t think enough about grabbing the odd suspended triad.
I can’t tell you I have a favorite sus2 form beyond the full barre with a 5th-string root, but working these out suggested some nice alternatives to work into progressions. In fairness, they are all triads, but I labeled the easy to grab three-note shapes as triads here.
Dominant 7’s cover the last remaining core 4-note chord in the arsenal. I struggle to employ them effectively in composition as well, but this one is clearly on me. Dominant chords are the heart of the blues and jazz and are no strangers to rock.