The people on the shake down cruise in green are the: NH Granite State Ambassadors.
http://nhgsa.com/
They are members of a volunteer organization that works to help promote the State of New Hampshire. You can find them manning the booth at the Manchester airport. The stereotype I have formed from meeting them each year on the shake down is that they are very nice people, often retired, who love New Hampshire and sharing it with people who may not know about it yet. They seem to have a very good time doing it as part of a team.