Listen to Slonimsky's Palindromic
Canon in 8 parts.
Here is a very cool eight note synthetic scale from Slonimsky's book. It is the first four notes of a Major scale and then the first four notes of a Major scale a tritone away.
It looks like this in the key of C:
You could play it over a Cmaj7 (#5) or a C7 (b13).
It has a lot of forward motion when played in it's ascending form, so it would work over a straight Cmaj7.
Here is a cool site on Slonimsky with audio and video clips.