I love blues and greens.  I've attached the String Cheese Incident logo if we could incorporate that somehow.  Each of their concerts is called "an incident" so this could be the Andrew Wolk Incident.  Also, because it's 60th birthday the traditional theme for 60th is Diamonds so it's also the Diamond Jubilee Incident in our minds.  We could incorporate a Disco Ball, mountains, a small wedge of cheese, 60th.  I know that's a lot of themes/ideas so just include some of them to make the logo look cohesive and not too jumbled.