A new computational model for fusion power plant system studies is being developed for the ARIES program. An operational design space has been created to explore the most influential parameters in the physical, technological and economic trade space related to the developmental transition from experimental facilities to viable commercial power plants. This allows examination of a multi-dimensional trade space as opposed to traditional sensitivity analyses about a baseline design point. The influence of multifunctional, highly dependent parameters can easily be visualized, which may highlight one or a few difficult-to-achieve parameters that would yield a highly acceptable design solution. The new ARIES systems code consists of adaptable physics, engineering and costing modules which capture the current tokamak knowledge database and reflect both near-term as well as advanced technology solutions that are higher risk but have higher performance potential. To fully assess the impact of the range of physics and engineering implementations, the plant cost accounts have been revised to reflect a more functional cost structure. All of these features have been validated against the highly respected ARIES-AT baseline. The present results demonstrate novel visualization techniques for trade space assessment of attractive tokamaks for commercial use.