I found some posing guides I liked a while ago and one dealt with group photos. A lot of the sample poses deal with smaller groups but there are a few for bigger groups as well. Here's the link:
http://digital-photography-school.co...oups-of-people
Another link to get some ideas from.
http://www.pinterest.com/mumtoelyse/...-large-groups/
One of the poses you should do is to have each person in the same position, perhaps with the same pose. (Which reminds me of the Nicholas Nixon series on the Brown Sisters).
I like the comfortable, informal feel.
One suggestion: the way you have people positioned, the top 40% of the middle is distracting, not-quite-empty but irrelevant space. I would try to get the faces higher.
Also, consider opening the lens up a little in order to get less DOF. You need enough to keep all of the people in focus, but the background detail is distracting. Alternatively, use a simpler background or one further back.
See if you can get them to wear clothing that sort of blends them together together. Big people (of any age) might be better shot wearing a darker, subdued color clothing...
I'm listening guys...![]()