Listening hang
JoeE has the right idea. I've been into jazz for years, but over the last couple of years, I've had the oppurtunity to have some late night "listening hangs" with a great, first-call drummer. It's a great education to have someone to suggest, then take you through the music while listening.
I listen classical music (Miles LOVED classical), but the more I listen, the more I really admire improvisational music.
Jaco is a must listen. As Pat Metheny said "Jaco may well have been the last jazz musician of the 20th Century to have made a major impact on the musical world at large."