Enterprise integration (EI) involves integrating business processes and data across organizations, systems, and applications and is a key spending priority for CIOs according to the consulting firm Gartner. Enterprise integration however represents an investment scenario fraught with a good deal of uncertainty on account of rapidly changing markets, technologies, and standards. EI represents a rich and dynamic market with ever-shifting boundaries, complex XML-based technology stacks, and a proliferation of standards. Complex and uncertain investment scenarios are best approached from the increasingly important real options (RO) valuation methodology. This paper develops a taxonomy of use cases of enterprise integration, assesses the uncertainty inherent in these use cases, and then develops decision-making heuristics based on the RO notion of Strategic Net Present Value (SNPV) for approaching investment decisions in EI.