Zulfiqar Ali Mir I have not seen a Bayesian treatment of Somers' D, to my knolwedge this is a research gap---and a very important one because Somers' D is widely used to evaluate the discrimination power of credit risk scoring models. A Bayesian approach to Somers' D will be useful to calculate the discrimination power of credit risk models in low-default portfolios.
You may want to consider Spatial econometrics. However, you have to provide a justification for the effect of spatial or regional influence on your study. I think this area is recently gaining traction.