Anyone considering applying to a university should visit it, if at all possible. Many people visit campus during the summer vacation period. This is convenient for travel, but not always the best time to get an impression, because most campuses are very quiet during the summer. Waterloo is a bit of an exception, since we have classes going throughout the summer for returning co-op students in engineering and other programs.
The fall is probably a better time for a visit, when things are more active and you can get a good feel for the campus in actual operation. Take a day or two off high-school classes and visit a campus! If you’ve never been on a campus visit try the closest one to home, even if you don’t intend to apply there. It’s good to get a practice visit so you know what to expect when you go to other places of more direct interest.
Of course, in some cases it’s not practical or financially feasible to visit a campus that you’re interested in. In that case, using online videos is one way to get a bit of a tour. I think that most universities have some sort of video tour availability. Here’s a recent video made by one of our own class of 1998 civil engineering alumni, Fanny Dunagan. It’s interesting to see what captured her attention when returning for a visit.