After watching the MIA-CHA series and seeing all the minutes the goggled Chris Douglas-Roberts is able to play by default, I have been thinking along the same lines as the OP that Jeff Green and Charlotte would be a great match. The presence of MKG definitely makes the situation more tricky, but if either Green or MKG can be comfortable as a heavy minute bench player I really like the lineup flexibility for the '14-'15 Hornets.
Traditional line-up: AJ-McBob-Green-Henderson (or FA SG)-Kemba. Insert MKG for Green for more defensive look
Green Stretch 4: AJ-Green-MKG-SG-Kemba. Green and MKG both can defend wing, Green can guard PF, and both guys can hold own on the glass.
Small ball: McBob-Green-MKG-SG-Kemba. If they find themselves "Hibberted" in a matchup like Indiana has with the Hawks, this more mobile 3 point shooting lineup should hold its own.
Wing heavy defense: AJ-McBob-MKG-Green-Kemba. I could see having MKG and Green on the court to tag team defense on a wing scorer like Lebron, Melo, etc. while still leaving a reasonably potent offense.
Jeff Green's flexibility definitely makes him an appealing player to have on an NBA roster IMO. In fact, I will not be at all sad if he is still a Celtic come next year. That said, I think he will be much more effective when he can just be one of the guys, and not need to shoulder the load that Boston will need him to (and he really isn't capable of doing consistently).
If CHA have interest in Green, and can get MKG comfortable that they aren't giving up on him, I think they have the right assets to make an attractive offer to the C's (picks, Biyombo, Zeller, Taylor are all interesting) that I'd be in favor of taking, and it would probably be to the long-term benefit of Jeff Green's career to make the move too.
ATL also seems a good fit for Green, but the Hornets are the team I've given more thought to.