We describe a middleware framework conceived to enhance the effectiveness and efficiency of existing simulation applications by providing three capabilities: (1) access to grid-based and cloud-based execution, (2) access to advanced Design of Experiments (DOE) methodologies such as simulation-based optimization, and (3) access to robust data processing and visualization. The framework has been applied to a variety of simulations in both commercial and open source programming languages employing both discrete and continuous modeling formalisms. A key design objective is to minimize the workload necessary to adapt a simulation for use with the framework. User experience to date reveals that the learning curve for the framework is reasonable, but further automation of key tasks would enhance the framework's utility.