I think that the best type of graph for showing Flores del Mundo’s membership trends over the course of the year is a line graph. This is because line graphs are generally the best to display how values (membership) have changed over time (the year). A line graph will clearly show movement throughout the year.
If graphing total membership vs employee/spouse/dependent, I would use a bar graph which is useful for focusing on individual values while also comparing the data.
For showing Eastern and Northern Membership on the same graph, I would use a bar graph similar to the right graph in Figure 1 from Few’s article since there are 2 sets of categorical data: time and region.