Depends on what you want to get out of the visit. You should know to some degree ahead of time if this school would be your sons "dream school" or is this visit just weighing possible "options" down the road? We used the unofficial visit as an opportunity to look at the campus, the baseball facilities, student housing, the town in general, and maybe pick up on the coaches’ personalities. On a few unofficial visits we never even talked to a baseball coach. What Lafmom suggest is a good approach with good questions. Most wouldn’t do it our way but it was our personal choice NOT to pre-arrange an unofficial visit with the coaches. We didn’t want a “dog and pony” show but just wanted to “drop in” and see things on a “normal” day. If you do talk with a coach you can discuss anything you want since you are on his campus. I wouldn’t ask presumptuous questions or I wouldn’t close any doors on the first visit. I would classify an unofficial visit more as a feeling out process for both sides. This is basic but I'll say it anyway. Your son should understand that first impressions are lasting impressions and to dress accordingly. Some coaches are a little quirky about their players’ appearance. My son even shaved his goatee after viewing one teams roster on the internet.
Good luck,
Fungo