We present a system for describing and solving closed queuing network models of the memory access performance of NUMA architectures. The system consists of a model description language, solver engines based upon both discrete event simulation and derivatives of the Mean Value Analysis (MVA) algorithm, and a model manager used to translate model descriptions to the forms required by the solvers. A single model description file is used to describe the essential elements that characterize the NUMA system and its workload. During a single simulation or MVA modeling run it is easy to dynamically vary elements of the system model, such as mean device service times, elements of the workload model such as cache miss rates, or both. Use of the extremely fast, but approximating, MVA solvers to interpolate between design points computed by the slower simulator allows the analyst to obtain detailed and accurate results in minimal time.