Visiting is helpful but not essential. If you can swing a few visits on one trip (driveable from the same airport, like you said), or if your kid is eligible for a fly-in, then go for it. Seeing a variety of schools can help your kid figure out what they want in a campus, what they’re looking for in a vibe, and they might learn about some resources that would be harder to find out about otherwise.
But don’t go crazy or go into debt if you can’t visit all or even most schools. A few thoughts:
My S26 learned a lot by tagging along on D23’s visits, even if he was just a rising high school freshman at the time. So if you can take them both, then do (I realize that makes the trip more expensive but could pay dividends in the long run).
There are lots of ways to interact with schools that don’t involve on-campus visits: virtual tours and info sessions, interviews, and any other Q&A type events the admissions offices might offer. Take advantage of these.
For D23, her top three choices after all the decisions were in turned out to be schools we had not visited. All three were within driving distance of the same airport, so we could do a quick swing through, scheduling around the admitted students’ day at one of those schools (which was the one she chose, in the end). So it’s really not essential to visit before applying, although it’s a good idea before committing.