I would recommend visiting if you can - especially U Chicago. We toured both NW and Chicago with our D and she loved both. Evanston is easy to like and IMO the perfect college town. U of Chicago has a beautiful campus but neither H nor I could get comfortable with the surrounding neighborhood. We said nothing to D at the time, but decided to wait and see how things played out before discussing our concerns with her.
In the end she was admitted to her EA school which was her first choice so she never submitted the other apps. But I do think a visit to U of Chicago would be prudent if your son is seriously considering the school.