Statistics, Machine Learning, and Data Visualization

I recently complete my Master of Arts degree in a non-quantitative program. As an undergrad, I've taken nothing above one semester of calculas. During grad school, I had three statistical methods courses on OLS, Logit, Probit, etc.

I'm now running an analytics company which helps small business clients with data analysis and visualization. Much of what I am asked to do is simple stuff, univariate distributions, OLS, etc. However, I've been thinking about returning to school to furture my education. I could pursue a BS in statistics, or I've considered the iSchool at Berkely.

Does anyone have any suggestions regarding the next step in my education? Should I go back to school? What program?