Although not essentially complex in "jazz theory," Duke Ellington's Sophisticated Lady reveals some interesting musical strategies:

General Analysis:

Beginning in the key of Ab Major, Ellington already gives us interpolated chromaticism between the Bb-7 and Eb7 which occur in the first and second measures. Directly after Eb7, he presents us with a tonic diminished chord leading into Ab Major7. This is particularly tasteful placing it at the end of a string of chromatic chords and a strong dominant. It is worth noting in measure four of the repeated chromaticism to support the blues melody preparing us for the proceeding V/V. In measure seven, Ellington chooses chords Ab7 and F7b9, by no coincidence. Not only do these chords share three identical notes (c,eb, & gb), the last note of both chords (gb) is taken from the Mixolydian mode, giving us a b7 in the key of Ab. He also uses the lowered 7 by adding G7 chords in measures 13 & 17. In measure 13 he treats this as leading to the vii/ii. In measure 18, it could also be thought of as a V/iii. Measure 19 has a creative turnaround on the Eb7 chord, as it is set up for a bassist to perfectly accompany to the C-7b5 by playing the Db in between.

Keys:

Ab Major, G Major

Modulation:

The modulation appears to be direct, in measure 10 we have a ii - V progression in the key of G Major, not sharing a pivot/common chord with Ab Major.

Form:

The form of this song is typical AABA.