I think that when you are dealing with adults, age is not such a big issue. They all have opinions, knowledge of the world and are able to discuss them.
Try to choose topics that will interest all of them, or at least topics that everybody can contribute to. It might be interesting to compare what the people in their 60’s and 70’s used to do on Saturday nights with what the younger people do on Saturdays. You could compare other topics such as marriage proposals, first job interview, time at school…. However, I wouldn’t be careful about doing too much of this as the students could get tired of it. You will see their reactions for yourself.
When doing pair work, sometimes pair students with somebody of their own age group and at other times, with somebody of a different age group. You can also also them to choose who they want to work with.