The day started off great. We had breakfast in the hotel, went to lunch with one of the program directors, and then toured the town with grad students. Later, we went to a hockey game and had dinner with grad students in the next town over.
Then, for reasons I cannot divulge, I fell out of love with parts of the program. I saw a very dark and disturbing side that I had not expected. For that reason, now I am considering another school that I have an interview with in a few weeks.
I've learned a lesson today to not get your hopes up and not to put all of your hopes into one opportunity, especially in academia. I'm not going home as excited as I thought I would be. If anything, I am disappointed. But I'm going to move on and start looking at all of the options that are out there.
Edit: For any applicants who need help with what questions to ask at interviews and how to decide if the atmosphere of the department is for you, I highly recommend this webpage: http://www.esa.org/students/section/node/412