When you think group shots, what lens immediately comes to your mind? Often, the initial reaction to a "group picture" is to reach for the widest lens in your bag. It's a safe option that makes sure you'll fit everyone in the frame. It could be said group shots are more about accounting for everyone who was present rather than being a work of art. However, if you care about the quality of images you're creating, maybe your widest option shouldn't be your default.
I've been a wedding photographer for a few years now and have had a chance to compare different perspectives of the same shot. The more I've shot, the more I've felt that in general, a group picture looks better when it's zoomed in. Here are a some comparisons of what I mean.
*Note that all focal lengths were shot on a crop sensor. I did not factor in the 1.6x addition to the listed focal lengths.
By backing up and using twice the zoom, I was able to simplify the subject matter within the shot and frame all of the group within the trellis.
By backing up and zooming in, I was able to eliminate a lot of the distracting buildings on the sides of the picture.
By backing up and zooming in, I was able to surround the couple with only live oaks and remove the distracting breaks in the trees and house from the edges of the shot.
As you can see, there can be great benefits to choosing a longer focal length for posed photos. When you have the room to step farther from your subject, you gain control over what background you want to include in your shot. It is far easier to remove distracting elements from the scene and keep your pictures looking clean. As well as a cleaner background, you also can create a more beautiful bokeh with longer focal lengths. When you double the length of your lens at any given f stop, you decrease your depth of field by half. Shooting f 2.8 on a 50 mm will give you a little less than half the depth of field than f 2.8 on a 24 mm.
Of course, there is always a time and a place to pull out a wide angle lens. There are instances where you simply cannot back up, you may find the perspective is better from a close distance, or you simply may want to draw attention to one subject within the group. Though you shouldn't neglect your wide angle option, next time you have a group in front of you, consider if your shot could be improved by backing up and zooming in.