Watch the Triads 2 online guitar lesson by John Stowell from Modern Chord Melody
Triads 2 "Haiku" has a number of dominant chords with tensions/embellishments, and I try to reference those sounds as I solo to give my improvisation some context. Just as major triads work well in a variety of keys over a major chord (see the previous video "Haiku"#4 video#1), they can also be used effectively over a dominant chord. Over a C dominant, I will use C#major triad (C7#5 flat9), D major triad (C6/9#11), E flat major triad (C7#9), F major triad (C11 6/9), F# major triad (C7 flat9 flat5), G# major triad (C7#9#5), A major triad (C 13 flat9), and B flat major triad (C 11 w/9). Because the major triad is such a pure sound, to use it in multiple keys to generate more complex harmonies lends a special quality to your improvisations. With any substitution, move slowly and evenly between the original sound and the substitution (in this case the dominant chord and nine major triads) to develop facility and a melodic concept. You may notice in my solos that I favor wider intervals. I've found over time that it became easy to displace octaves and use unusual note combinations as I internalized scales, arpeggios and substitutions.
"Haiku" also contains a number of minor chords, and major triads can also be used effectively over them. Over C minor, I will use D flat major triad (Cm11 flat9), D major triad (Cm6/9 flat5), E flat major triad (Cm7), F major triad (Cm 11w/6), F# major triad (Cm7 flat9flat5), G major triad (Cm Maj9), G# major triad( Cm7#5), B flat major triad (Cm9) and B major triad (Cm maj7 flat5). Obviously some of these sounds are more abstract than others, but all are usable in some context. The instrumentation of the group will be a factor in determining the amount of freedom you can exercise harmonically. If I'm playing alone, in a duo with a bassist or in a trio with bass and drums, I can determine the agenda harmonically. If the group contains piano or a second guitar, then I'm also responding to the content of the accompaniment. I enjoy both situations; a variety of challenges interacting with different musicians keeps things interesting. I haven't discussed major triads over half diminished or diminished chords, but there certainly are applications there. Minor, augmented and diminished triads are also used in a wide variety of substitutions.