Modal chords can change the feel of a song to an amazing degree, as can suspendeds and a number of other slightly altered forms. Ninths as well. A lot of the punk (and metal)bands use chords with no 3rd and it give a stark, hard feel to them. Hard to explain it with words, but they seem "dangerous" to me, which can add tension to a song when you want it. One of my favourites is an "E" modal chord up at the 7th and 9th frets.

Play E note on 5th string 7th fret. "B" on 4th at 9th fret. "E" on 3rd at 9th fret. Now strum all six strings hard. It's a very resonant "E modal". Gordon Lightfoot used it on his song "Sundown" I think.

Great job Jo. Hope you can get your process down from 9 hours!

Rick