We all love doing group portraits. Not.
Whether it is an undisciplined family group at a party, an overly-disciplined regimental portrait, or just wedding guests gathered around the wreckage, the shoot can be difficult to do, and the results patchy.
The family party is composed of people who will not obey - the relatives and children. They will be difficult to marshal into one area, will insist on changing places continuously to gain precedence, and will never ALL be looking in the same direction.
The regiment or ship's company CAN be compelled to sit or stand in order - correctly - and can be ordered to all look toward the camera with no-one making Indian feather fingers. But you won't be the one doing the ordering. For that you need the senior warrant officer. Contact him early on, do as he says, and he will deliver the goods.
The wedding group includes the bride and groom and their parents - who are paying you to be there. Put them in the center, expose so that they look good, and let their relatives fall as they may.
All this said, there is one problem if you have a large group to photograph that spreads wide in front of your lens - you will be forced by the geometry to use a wide-angle lens and that in turn will force you by the nature of optics to get distorted faces on the outer edges. Faces that started out round end up flattened like pumpkins. Grins become maniacal.
If you can get the group to curve round you like the horns of a buffalo, you can reduce this. If not, try getting one of the DxO Viewpoint 2 programs - you can plunk it into a number of Adobe photoshop programs - both regular CS. PSE, and LR, as well as Aperture 3.
It will perfectly correct the distorted faces at the edge of the frame without narrowing to ones in the middle. If you have jiggered up architectural shots it will straighten and correct the distortion. You'd be surprised just how much better this makes even studio shots when you are using extreme wides but have let you camera deviate from the horizontal ever so little...