[quote="river"] Would it be possible to visit Columbia, NYU and Yale within 3 days (since they are all in NY) and Kellog, Chicago, Michigan within 3 more? What is the preferred way to move to the other cities (e.g. New York, Boston, Chicago, etc)? What is the best sequence to visit all of them? [quote]
You can definitely do both these options in 3 days. I would advise against fitting 2 visits in one day since most schools have detailed campus visit programs with lunch/class visits etc. and they would definitely clash. I would also add you can take a train to philly from NY and knock out NYU, Columbia, Yale and Wharton in 4 days.
For the NY schools, you can visit them in any order. For Yale, take the train from Grand Central to New Haven. For NYU and Columbia, you can get to them by subway. Also you can just take the train all the way to Wharton from Penn Station.
As far as Boston is concerned, you can either take a bus and save money, get there in 4 hours from NY or take a flight/Amtrak (more expensive). I would suggest taking the bus because its cheap and convenient and you have wifi all the way through.
For the Chicago schools, you could try flying into detroit, visiting Ross and then renting a car and dropping it off in chicago or vice-versa.
Let me know if you have any other questions.