1. An iterative drilling simulation method for enhanced economic decision making comprising: obtaining characteristics of a rock column in a formation to be drilled, wherein the characteristics of the rock column include at least one of the following selected from the group consisting of lithology, rock strength, and shale plasticity, wherein obtaining the characteristics of the rock column includes deriving a respective characteristic from log data and a respective lithology model, rock strength model, and shale plasticity model, further wherein the log data includes at least one of the following selected from the group consisting of well logs, mud logs, core data, and bit records; specifying characteristics of at least one drilling rig system, wherein the characteristics of the at least one drilling rig system include rig inputs wherein the rig inputs include at least one of the following selected from the group consisting of: operating constraints, rig costs, maximum weight on bit, top drive torque, table drive torque, top drive minimum RPM, table drive minimum RPM, top drive maximum RPM, table drive maximum RPM, pumps maximum GPM, and standpipe maximum PSI; iteratively simulating the drilling a well bore in the formation and producing an economic evaluation factor for each iteration or drilling simulation, wherein each iteration of drilling simulation is a function of the rock column and the characteristics of the at least one drilling rig system according to a prescribed drilling simulation model, wherein the drilling simulation model includes at least one of the following selected from the group consisting of a mechanical efficiency model, bit wear model, hole cleaning efficiency model, penetration rate model, and drilling economics model; determining whether an iteration of the drilling simulation is optimized according to a prescribed optimization criteria; modifying the characteristics of the at least one drilling rig system if the iteration of the drilling simulation is not optimized; and generating a recommendation package of drilling rig system characteristics for use in a drilling of a wellbore in the formation as a function of the economic evaluation factors if the iteration of the drilling simulation is optimized.