I am not going to the Prospective Student's Day, but I did visit in the fall. I would suggest flying into Midway if possible because it is so much closer to campus than O'Hare. You can take a bus from the Midway to UChicago for just a couple of dollars and it took about an hour to get to the school. Also Southwest Airlines flies into Midway and they tend to be less expensive than other airlines. Good luck! I know how all of those travel expenses add up!