Yes, plan to visit each school your student may be interested in attending. If you are using the visit to determine whether or not to apply, plan those visits in the junior year when the student has a school break. Make sure the college or university is in session, so you can talk to current students. Plan your visit through the Admission Office, even if you know someone on campus. That way, your son or daughter will get credit for the visit since that is one of the best ways to show interest in a school.
Plan to eat on campus when you visit - either at the dining hall or student center - in order to interact with more current students. This allows you to talk to students and faculty who are not part of the admission tour and can help your student determine if the school is somewhere s/he will fit in.