IN DADGAD,youcan playa d modalchord or dyad, dadaad on second fret third string ,with one finger.you can also play daddad with one finger on third string 7th fret, or dadddd two fingers on 7 th fret,second and third strings,three different, d modal dyads or chords.
In STANDARD TUNING lots of different two fingered e7,and 2 two fingered a 7,are available,two different inversions of d major[apart from barre versions]an e modal ebebbe,two different a minor chords,two different a major chords,as well as long a [a modal].
if you use the middle four strings only,c modal and g modal and your ordinary d major becomes d modal,if you stretch your pinky to the first string, d modal on five strings,[E]ADADA.I find standard tuning good for a minor and a major,keys I sing in quite a lot..BEST Thing is to draw guitar fingerboard in diagram,then you see them.hope this helps.look out for a major, e 7, and d major around the fifth fret.