My older kid was a reasonably experienced traveler, and flew to accepted visits alone with no trouble. Younger one less so, so I went along for hers.
Remember that you are thinking of making a big expenditure for college. In the scheme of things, a plane ticket to make sure the choice is solid is probably worth it. Even if you can’t book it until a few weeks before the dates. Also, my kids didn’t go to accepted visits at every school, just their top 2-3 choices they got into.
Sometimes you can ask on ED threads if the accepted students have heard about dates for accepted student weekends.
A few schools my D2 got into offered her vouchers to cover some of the cost of the visit. They were private schools, though.