The offshore wind industry is shifting its focus towards deeper water sites, more suited to floating rather than bottom fixed support structures. Floating support structures currently used for oil and gas platforms provide a starting point for the floating wind industry; however, the selection of an optimum structure is not trivial with several unique factors that contribute to its complexity. In this work programme, a methodology to rapidly assess several concepts for wind turbine floating support structures is proposed. Using the multi-criteria decision-making method, TOPSIS, configurations are rated for a range of attributes. In addition, two complementary methodologies have been developed that extend the TOPSIS capability by including an estimated impact of the uncertainties associated with each of the selected criteria, on the final choice of an optimum support structure. This methodology represents a robust yet flexible design tool to complement the early conceptual design process that is able to rapidly investigate a broad design space and narrow down the number of potential options suitable for floating wind turbines.