I agree with everyone's comments that your multilevel contextual factors are quite interesting and that thinking about what factors might mediate findings of associations by geographies or system is an important next step after identifying contextual assocaitions. Other things to consider include things like community-wide technological literacy and immigration (both in and out).
For modeling SES, considering SES a confounder, or "third variable" is definitely an option, with GEE or regular regression models. Also think about the possibility for SES to be an effect modifier.