Hello, and welcome...
I enrolled at Marshall, originally from the great state of Pennsylvania, all the way back in 2003.
Marshall has a beautiful campus. Visiting on a football game day would probably be the most fun, especially if your student is a sports fan at all. Traffic on game days isn't terrible with the exception of roughly an hour before the game and about an hour afterward. Typical of major events in urban areas.
I know tours are done every day during the week and on certain Saturdays. When I came down for a visit when I was a senior in high school I took a tour on a Saturday (we were driving down from our home near Erie). We were actually a little late because we got stuck in road construction and the tour guide was very accommodating and waited for us since we called ahead.
Here is the link to the tour info.
https://www.marshall.edu/recruitment/tour-our-campus/
As for pros and cons of coming to Marshall, all I can speak from is my experience, but I consider getting away from my hometown and coming to Huntington one of the best decisions I have ever made. I was able to get involved with campus activities while living in the dorms, made friends quickly and got a part-time job shortly after getting to Marshall. There are so many clubs, organizations, student groups and activities that it's very easy to integrate into the college experience.
Hope that helps!