Have you tried playing with add9 chords? Actually, any guitar player who has bashed out some classic rock or 80's power ballads has probably been playing a Cadd9 without even realizing it. Shown below is the Cadd9 as a guitar chord. Piano players or other instruments use the notes under the chord box to come up with your own variation.
Of course, any chord that adds a whole bunch of new notes is generally harder to play. The add9 chords, um, add an awesome amount of 'airiness' to your chord sound. Below is the a minor add9 chord on a piano and guitar.
To create an add9 chord simply add the note which is a whole tone above the octave of your root note. In the example above the 'D' is a whole tone above the C octave and in the example below the 'B' is a whole tone above the A octave. See if you can create your own add9 voicings. Experiment with your keyboard by doubling up some notes and see what sounds you can achieve. If you're a bass player try adding that 9th note into your bass lines. Guitar players will find playing a lot of add 9 chords quite demanding. We'll post other version from time to time in our music lessons, but you can move the shape shown below up and down your fretboard to create other minor add 9 chords, just like you do with any barre chord.