if ypu're also interviewing then of course business formal. You could definitely get awake with business casual for a simple visit

I went business casual (meaning a sweater and khakis is appropriate for men and women) for my class visits. This way I didn't dress too formally because I knew that not everyone was going to class all dressed up, but I didn't want to dress too casually because again, these schools' admission reps and everyone in the class is looking at you as the newbie.

I typically just dress in jeans and t shirts to work, so dressing up to business casual is like dressing up to me, so I had to change before my class visits because I applied to a PT program.