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.