“I’d prefer a Wall Street job to one in the Silicon Valley”
Since this is the fist criterion you list, I assume this is probably the most important factor for you in determining a school. If so, the following is my 2 cents.
Yale economics is going to help you more on this regard. Economics and finance majors in MIT at the undergraduate level are actually not popular. According to the following: http://web.mit.edu/registrar/stats/yrpts/index.html, the % of the two majors is probably only 1-2% of the entire MIT undergraduate population (I hope that I did not read it wrong). Given this small number of students, one would expect far fewer wall street firms recruit on campus at MIT than at Yale where economics and economics & math major accounts for around 15% of student population.
My S is at Yale. He has already had plenty opportunities to network with major banks as a freshman on the campus. The ranking of economics department is really not relevant here. This type of ranking is mostly driven by the strength and the size of doctoral program. Yes, MIT and Harvard are power houses in this regard. But this does not translate to the undergraduate level. They are different animals.
For wall street jobs, HYP and Wharton are core schools. Although Columbia is traditionally not regarded as a core school (it tends to be viewed as a target school), its placement into wall street is actually on par or even better than some of HYP and Wharton. Beneath the core tier, we are talking about target schools. MIT is more of a target school, not because of its quality (very, very high quality), but because of that the depth of undergraduate candidate pool is not as deep as the core schools.