I've heard the day ends about 3-4 (confirmed by schedule from prior interviews that states your day ends with interviews at 2, then apparently you meet with the dean for 10-15 min + goodbyes, etc.). I think their site/literature/email suggests that you book relatively late flight (after 6 i think). Flight out was a bit of a problem for me (more cost), so decided to fly out next morning. Extra hotel room cost less the cheaper flight worked out cheaper (and time to relax). Priceline it for $50 bux and you should be able to get Wyndham hotel like I did if interested.
Plus...independence airlines has cheapest flights I was able to find (assuming they fly into your city)