In designing large-scale pipelines and facilities, a common trade-off involves cost versus risk. The conservative design margins of the past may today be the tipping point in making projects non-economic. This paper aims to identify critical factors for facilities design projects with an objective to increase the confidence in our go-to-purchase decisions. A practical decision making procedure applicable to flow assurance problems in general is presented that considers both rigorous multiphase pipeline simulation as well as facilities costs. A case study previously published in a PSIG paper is revisited to illustrate how these concepts may be applied in sizing a slug catcher.