Make sure your son meets with coach to let him know why he'll be gone, then take the trip. If the coach has a problem with your son visiting a college that may be able to offer him the chance to play baseball at the next level, then I would have a problem with that coach.
This is definitely something both you and your son shouldn't feel guilty about. It'll be fine.
Totally disagree with this way of thinking. He can make the unofficial visit at another time. He should not miss the game. This wouldn't go over well at my son's school.
One of our recent experiences, was an interaction regarding an Official Visit. The coach offering the Official, mentioned whether son could miss a practice for the visit, if it was on Friday. He said if there was a game that day, they would fly him in on a Saturday. So I would think that if the coach has the kid's best interest at hart, he wouldn't ask Jr. to miss a game for an unofficial visit. There is plenty of time for that IMHO.
Hey, feel free to disagree all you want. That's the beauty of this board, it's all about different (and differing) points of view.
It's also why Baskin Robins makes 31 flavors.