In this paper, we aim to provide a methodology for designing IT-enabled service systems and specifically focus on front-end customer services. When the focus is on front-end customer services, the interactions among agents involved in the service system become predominant. A good service design should fit the needs of customers as well as bring values to service providers. However, agents usually have different perspectives toward the value propositions of service systems. While these agents involve in the value co-production process, how to design a service system that can balance among different value perspectives become a significant research issue. After defining critical components of IT-enabled service systems, we propose a service choice theory to resolve potential value conflicts in value co-production process and apply Arrow's impossibility theorem to strengthen our argument. A solution that applies quality function deployment framework is then proposed to achieve the fit between value components and service offerings. At last, we use the u-health service system in National Taiwan University Hospital to illustrate how our proposed methodology is applied to design an IT-enabled service system.