I think your decision is not so much NYU vs Williams but rather business school vs liberal arts. Once you make the second decision, the first one will fall in place.
It sounds as if you’re leaning toward the breadth and flexibility of the liberal arts degree. Many Williams students – in economics, math, and other majors – end up on Wall Street or in financial consulting or economics driven NGOs. Placement for summer jobs and internships is excellent as is the alumni/ae network.