Geomagnetic disturbances (GMDs) caused by solar storms give rise to geomagnetically induced currents (GICs) in the power grid. GICs may affect transformers by hot-spot heating and damage, and increase reactive power losses in them. They may also cause harmonics, protection device misoperation, and loss of reactive power resources, potentially leading to a voltage collapse. This paper presents GMD analysis results of a large-scale power system, using the recent NERC GMD benchmark scenarios of non-uniform peak electric fields, to highlight the differences in results compared to the hitherto-conventional approach of using uniform electric fields for planning-type GMD studies. In addition, two types of parametric analyses to study the impact on steady state voltage stability are presented, 1) including transformer reactive losses from neighboring regions around a certain footprint to analyze the impact of study-system size 2) varying substation grounding resistances to understand the effects of their uncertainty.