there are many ways of doing the whole away rotation thing...however, when it comes to NYC rpograms they all compete against each other. It is purely a pride thing, so do a rotation at one place and then make sure you use the letter in your application to others...risk is that they will know you did an away rotation elsewhere and not w/ them. It doesn't matter which one of the big three you go to, but if you can go to more than one do it... we have people at Cornell who did 3rd year rotations at all 3 (cornell, Sinai, and Columbia) and it helped them make up their minds... in the end it doesn't matter..got to have the numbers, but that's a whole other post that's already been done.