What aperature is good for shooting a group of people with Canon SLR?

1. Larger f-stops numbers mean smaller apertures.
2. Smaller apertures mean more depth of field.
3. Longer focal lengths (IE the long end of your zoom) mean shallower depth of field.
4. As a general rule, depth of field is 1/3 in front of the focus point and 2/3 behind…. so generally err toward the front of the group on point-of-focus.

Calculating depth-of-field specific to your situation is easy:
http://www.dofmaster.com/dofjs.html

f.22 Nice and detailed.

Illustrated photography gives a good explanation with images.

17-55mm F2.8 i guess? Hmm A few infront a few behind. I often use F5.6 for group photos, when they are standing 2 to 3 rows back. But when its 1 row, i put at Either 2.8 or 3.5. When you focus, focus the front row’s eyes, anyone of them.
IF you use your widest 17mm to frame them, 5.6 for 3 to 4 rows of ppl back should be fine, but if you use 55mm to shoot 3 to 4 rows of ppl back, try putting up to 6.3.
Remember
Longer Zoom = Shallow Depth of Field = Blur background
To compensate the longer zoom, shoot up your ISO and decrease a lil shutter speed.
Im using Tokina 10-17mm Fisheye, so aperture doesn’t really affect me =)) Hope this helped you, instead of reading up so much of those pro tips… =D