JohnHardly,some of the versions of a modal and a minor,andE modal,which work very well in standard,are more limited in dadgad,and double drop d,these two tunings are IMO,suited for g and d.Using the top strings as drones,to produce interesting passing chords.
The point about standard,is that you have E and B ,as ones top two strings,standard is a tuning that is very flexible,but because your top string is E,To get the modal sound youare restricted to e and a modal and minors
IN DOUBLE DROP D,you have BD,in DADGAD A and D,you can use these as drones,to create interesting passing chords in these keys,G and D.
so in answer to your question,chords like A minor modal AND E MODAL that use ringin [open]strings,and can be found found right up the finger board, in standard,RingingOpen strings ,is what the modal traditional sound is about.