Hi Mr/Ms. Lizzy,
Maybe I can add my 2 cents because I just visited Western a couple of weeks ago (although I was visiting the Business School).
I live only a couple of hours away, and the visit only lasted a few hours. I didn't get a tour of the campus or city. But my department has a separate Grad Day which does cover that, along with panel discussions and a meet-and-greet.
I wasn't sure what to wear either, so I contacted the administrator in the PhD office. Even though my visit happened on a Friday, she advised me to dress formally (jacket and dress pants). Whoever is helping you plan your visit will probably be very willing to answer your questions. Don't be afraid to ask. If I was putting myself through a 15 hour bus ride, I would make sure I knew what I was getting into!
I had a list of questions ready in my briefcase, both for the professors and the current grad students. While the faculty are more concerned with making a favourable impression on you (so that you accept their offer), the students are not as much. This means they can give you lots of great information about what life will be like there for a student - both good and bad. Every student I met gave me invaluable information. For example, I had a lot of questions for the woman who is currently working under my potential advisor...
Make sure you remember everyone's name so that you can email them your thanks later. Also, keep in contact with the students if you meet people you liked. It will be helpful when you think of more questions after your trip, which you will. And staying in touch means you'll start your program with a few friends, which never hurts. One of the students I met has already sent me several articles to read. Another sent me the name of a book I'll have to read in first year. I've already ordered it so I can get a head start.
I really enjoyed my visit, and came away excited about the idea of studying there. I hope you do, too.
But you have to tell me something now. You're not used to being addressed by your first name? That's so surprising. Where did you study where that's unusual? I'm going to scroll up to fix my salutation now.