The ii-V-I (or 2-5-1) progression is one of the most common and important progressions in Jazz music, and is found in almost every standard. Knowledge of the progression and how to navigate it will improve your improvisation and visualisation technique over changes, but also as a method to introduce a little "dirt" to your rock playing. The ii-V-I is not just limited to dingy little clubs where some guy takes a 28 minute solo on a clarinet!
In essence the progression is formed by building chords from the ii, V and I from any given key; so in C
Dm7 - G7 - Cmaj7
this takes advantage of the tension created by a dominant 7 chord and resolves to the tonic.
Of course a seasoned Jazz player will freely extend these chords with all manner of alterations, so don't feel confused by wacky looking progressions such as
Dm9 - G7#5b9 - Cmaj13#11
We still have the same root movement which creates our resolution, we have just added more tension in the right places for a little aural spice.
I cannot recommend this progression enough. As a young rock player it was the lines of Charlie Parker that brought a huge amount of chromaticism to my otherwise tired shred clichés, eventually leading me to fall deeply into rock fusion. Some of these idea would give an angry rock solo some real edge!
Michael Brecker ii-V-I
Our first lick is a Bbmaj run in the style of the late, great saxophonist Michael Brecker. This line is very similar to his playing in the funky outfit "The Brecker Brothers" alongside his brother Randy (Though Michael would have played this line as an insane run of 32nd notes!)
Over the ii chord its seems that Micahel uses the "pentatonic up a 5th" substitution, basing his line on Gm pentatonic (for more info on this substitution check out THIS). We do have some chromatic embellishment; the 1st note moves chromatically up to D then we descend down chromatically from F to Eb. This the ascends up slides to rest on a D (the 9th). Remember that this is a saxophone line so there is no correct fingering, only what works best for you.
Over the F7#5 we have a line that focuses on the #5 (C#), b5 (Cb/B) and #9 (G#) but the use of chromaticism leaves you questioning exactly what scale Brecker is thinking of. I would say that this is irrelevant, the idea is to create tension over this chord and resolve it effectively to the next chord, in this case the 3rd of Bbmaj7. When it comes to this sort of approach it may seem odd, but all the "wrong" notes are the "right" ones, so start playing around with the superlocrian scale (R,b2,#2,3,b5,#5,b7) and experiment by adding chromaticism to this. The following two shapes are a great starting point to practice this idea of tension and resolution.
Pat Metheny ii-V-I - Extending the Tension
This ii-V-I is a "quick change" in Bb. This means that instead of playing the ii and V for an entire bar we up the harmonic pace and move to two chords per bar. The result is that we have even less time on each chord, making outlining the change even harder! Fortunately there are ways to make this easier on you - using extended tension.
The basic idea is that a standard ii-V-I is a well crafted progression that sets up tension over the V chord which is resolved smoothly to the I chord, a perfect cadence. Over this V chord anything is fair game, as long as you resolve the tension created. So if we take that principal of "create tension - resolve tension" then why not ignore the ii chord all together and play out for longer? This idea is very common in bebop circles; a genre synonymous with tension/resolution and quick change ii-V-Is at tempos often reaching 200bpm!
So looking at our lick, you want to ignore the ii chord altogether; it is there (the rhythm section will be playing it) but we're thinking in terms of the V chord alone. Although this line features lots of chromatic embellishment (something common in Metheny's playing) the lick is clearly centred around F Mixolydian with lots of passing tones (instead of using another scale like F Superlocrian or F Half Whole Diminished), this is demonstrated in the diagram below. If you play the line slowly you will see that notes of the scale generally fall on notes 1 and 3 of out 16th note groupings (the strong beats) and out "oustide" notes fall on the weaker beats. The line is resolved by landing on the 3rd (D) of Bbmaj7 and then for colour I slide into the 7th (G), the 3rd and 7th of a chord are our "guide tones" and will always define the chord well, so use the idea presented at the end of the last lick and try to come up with your own smooth resolutions.
The other part of this lick to note is Pat's articulation; there is a very even blend of picking and legato and where possible the weak beats are picked and the downbeats are hammered/pulled to. This creates a beautiful illusion of swing, I have heard this described as 'swing picking', and helps to bring some attention to chromaticism present in the line.
Pat Martino ii-V-I - The Diminished Scale
This time we still have a quick change (in C), but instead we are going to be outlining both the ii and the V chord, something that some of the more hard bop guitarists like Pat Martino are absolute masters of.
Over the ii chord we are mixing D Dorian (D,E,F,G,A,B,C) and D Melodic Minor (D,E,F,G,A,B,C#) in position 4. Its very common to interchange the two sounds in jazz as the maj7 against the m7 of the chord is a beautiful tension note to tease the listener with.
For the V chord we are using the Diminished Half Whole scale -
G Ab A# B C#/Db D E F R b9 #9 3 b5 5 6 b7
As you can see from the formula the alterations contained within the scale are the b9, #9 and b5 meaning we can play this scale over altered chords without a #5 (eg. G13b9), It has a very modern sound and is a favourite of legends like John Scofield.
The diminished scale is a synthetic scale constructed of consecutive half and whole steps, this creates a symmetrical property that lends the scale perfectly to development as the same shape repeats every 3 frets. In the diagram below you will see the same shape played in different places on the neck, its important to see how in one place any given note in the shape has one interval but in another the same note will be a different interval in relation to the root, so always keep track of your root note and chord tones.
Analysing the lick you will see there are actually 2 licks presented to demonstrate how the symmetrical nature of the scale can be used to our benefit. Both licks start with the same phrase; but the first moves down to a diminished lick and resolves to C (the root of Cmaj7) whereas the second lick moves up to play the same lick geometrically but in a different area on the neck resolving to E (the 3rd). Try finding your own licks within the shape then experiment by playing it 3 frets higher and aim to resolve the lick in an effective way. This is a great tool for improvising because, unlike a scale like Superlocrian, you don't need to know several shapes to play the scale all over the neck.