Use Google maps to check the drive time between Northwestern and U Chicago, and check their tour times. It might be possible to do in one day . As for demonstrated interest, you do check in when you arrive for your tour, so that would mark your demonstrated interest(this is for any school). If you get short on time, or bored or tired, you can leave during your tour and no one will know or keep track. U Chicago is supposed to be a beautiful campus, also incredibly hard to get into, and has a unique culture (have you heard “where fun goes to die”), so if it is on your list at all and achieveable for you stats wise, you might want to try to check it out. But if you really aren’t that interested, you can get a feel for the campus itself (or any campus) just by walking or driving around, if you are already in the city. I don’t know that I would invest a few hours of tour time for a school that’s so hard to get into and that you’re not that interested in. There are non visit ways to show demonstrated interest if something changes later.