KG is my all-time favorite basketball player (sidebar: I don't count Larry Bird and Bill Russell, though I adore both, simply because I've been alive long enough to see KG's entire career. That's the only thing that gives KG the edge over older players), and was before he even came to Boston. The fact that he came to Boston, won a ring, and now plans to retire with the organization is a dream come true, for me, otherwise my favorite team and favorite player wouldn't be associated with each other!
Also, although it would be VERY fun to hear KG's commentary, I would be interested to see him try his hand at coaching. He has proven that he is an extremely intelligent player who understands the psychology of the game better than anyone else, and has a history of (at least on the defensive end) making everyone better. I think he has the potential to be a very special coach in this league.