Some couples ask their wedding photographer to photograph all or most of their guests during the wedding breakfast or reception. This is not an absolutely straightforward process. The bride and groom may have planned the seating arrangements in a meticulous manner so the people around each table are likely to be those who are closely associated or at least who get on reasonably well. However, there may be any number of tables to approach - typically between ten and twenty. Another problem is that of limited light. Receptions which take place in marquees during daylight hours are perhaps the easiest in this context, because the light is reasonably good and the fabric of the marquee acts as a giant softbox to reduce contrast.
Numerous approaches to the task are available, but it may be best to combine several techniques. It is certainly best to avoid a predictable table-by-table circle around the room. The people of the next tables will be watching and awaiting their turn, and some will be dreading the experience. A better approach is to pick out groups who look happy and as though conversation is going well, and get them to raise their glasses for the camera or something similar. It is usually necessary to reduce the depth of the image to achieve the required depth of field, so it may be appropriate for the men to stand behind the ladies' chairs. Then go elsewhere in the room and do another group - don't move incrementally around the room from table to table. It is too predictable.
A second approach is to ask who among the guests seated around a table has a camera. Many will carry one even if it is just a mobile phone camera. The photographer can then offer to take pictures of the assembled group using each camera, and can finally get a picture himself. Now move on again, apparently at random, and tell a suitable group how much they all seem to be enjoying the event, and what a good group they make. While they are laughing, get another shot. If time allows, the process can be interrupted for a while and then resumed at a later stage.