Consider a department store. Which departments probably should not be located near each other? Would
any departments benefit from close proximity?

In a department store there are a lot of departments that are purposely not near each other and some that are purposely near each other.

For example, typical departments include: women's clothing, men's clothing, children's clothing (both male and female), shoes, health and beauty aids, tools, camping supplies, home supplies, music, toys, etc. There are obvious non complimentary departments such as tools, health and beauty aids. 

An example of complimentary departments would be men's clothing and shoes. Another example is the whole children clothing department is located near to woman's clothing department. This is to attract mothers to buy something for their children.