I think my favorite modulation of all time is in Cole Porter's "True Love". I play it in A, and the modulation changes to C. The transition chord is an F where the melody stays on A during the shift, then to a C chord, then G, then C to E7, which leads back to A again.

At the first modulation from A to F has the notes move from A, C#, E to F, A, C. So, the A hangs in there, while the other two notes move one half-step, in either direction. When the focus shifts back "home", the notes are C, E, G, then E, G#, B. This time the E hangs on, while the other notes shift one half-step in either direction. There is an almost eerie symmetry at work that delights the ear. The song is so simple, but haunting, because of the use of diminished chords, and that wonderful modulation.

Bad modulations are a "pet peeve" of mine. The worst are those cheesy "slide up a half step, and if that wasn't cheesy enough, let's do it again". I always wonder if Willy Nelson suggested that silly slide at the end of "Crazy", or whether is snuck in after it was out of his hands . . .

Cool topic!
Emmit Sycamore