Thanks for your input!
I had the same impression of CHOP...the residents were not the warmest, but seemed nice enough. You can do whatever you want after residency, which is a huge plus, but I don't think the other programs would limit me in anyway. Philly seems like a fun place to live for a short period of time, too. The huge class size is definitely a downside.
I also loved UW. The residents were very friendly and very smart. They have a lot of autonomy and end up well-trained. Seattle also would be a great place to live. This is also a relatively large program (38), although the residents seemed to be closer than I observed at CHOP.
I wrote some comments about Stanford in another thread, but I did an away at Stanford and loved my time there. Morning reports and noon conferences were the best I've seen. Living in Palo Alto is a bit of a downside. I may have just been exposed to a larger sample size of residents because I was there for a month, but some residents seemed a little stuck-up. But there were other residents who were fun to work with and down-to-earth. The program takes great care of the residents.
For Columbia, I had a great interview day but didn't really know much about the program before that. The general reputation is that the residents work hard, but the program didn't seem at all malignant. I liked all of the residents I interacted with. It seems like a strong academic program but with a tight-knit group of residents (only 25). I loved the urban location and the patient population.