[Drew]

Have you looked at ways to get more mileage out of the arpeggios you already know?

Let's start VERY basic. Look at the notes in a Cmaj9 arpeggio: C E G B D

Now, because extended chords, in standard tertiary western harmony, are composed of stacked triads, be they simple triads or complicated chords with many additions, it stands to reason that if you're building up a third at a time, you can simply break any of those chords down to sub-triads and capture much of that sound, correct? So, here we really have three triads:

C E G - C major
E G B - E minor
G B D - G major.

So, if you're playing over a Cmaj9 chord, then any of those arpeggios will contain viable chord tones. An Em arpeggio against a C will suggest Cmaj7 (C E G B), whereas a G major over C will suggest Cmaj9 (C (E implied) G B D).

Likewise, if you want to imply a C7 harmony against a C, change that Em arpeggio to an Edim triad (E G Bb) and you're there. Do a fully diminished 7th arpeggio (E G Bb C#) and you imply a C7b9.

Against a C, a G minor chord, meanwhile ( G, Bb, D) would give you a G9 tonality.

You get the idea. Really, you can cover a LOT of ground with simple triad arpeggios if you learn your augmented and diminished patterns as well. Large 6 note arpeggios may be cool and all, but by then you might as well be playing scales...