Case studies are effective for exploring an issue when you are interested in the depth and complexity of the situation (as opposed to trying to isolate one or more specific variables). While it can be used to gain an "objective" outsider's perspective, it is most often used to understand the participants' perspective.
Generally, a study will only include one or two case studies given the time and effort each takes.
Resources for how to accomplish case studies:
Colorado State University Extensive Guide to Case Study Research
Illinois State University Guides for SoTL Case Study Research
Overview of case study steps from University of Texas Austin