I would not spend money you’ll need for the actual “college” part of college (flying a kid home at the end of a semester, for example) on visiting. I would make exploring the in’s and out’s of every college under consideration a family project. Someone to read the campus newspapers (both the official one and the “alternative”). Someone to get smart on the food options. Someone to research the local area- how many kids work in town, get internships, volunteer or start cool projects– etc.
of course a free fly-in is fantastic. But I think you can learn a lot about a college with some dogged research.