Upright Bass: Bb Major Pentatonic Over the Changes
Where Bb Major Pentatonic lies at this seat, and what a chorus takes out of it.
Bb Major Pentatonic runs 5 notes to the octave, laid out here on EADG with every Bb flagged. Mid-chorus the pattern is not what you need; where the root is when the chord changes underneath you is.
Open, sunny, and hard to play wrong — with no half steps there is nothing to clash, so every note sits comfortably over a major chord. Warm, folksy, and singable.
Heard in: Country, bluegrass, folk, gospel, Southern rock, and countless pop hooks — from "Amazing Grace" to "My Girl".
The upright takes a chorus less often than anyone, and that is exactly why these matter: the notes between one chord root and the next come out of a scale, and a walk that lands on the wrong one is the loudest wrong note in the room.
Play it slowly against the audio until it stops being a shape, then put it over two bars of a form and let the chord tones decide which of the notes you actually keep.