MB:
More than what you should ask or say is what you should do (prior to the visit).
*What connection do you have to the school/link? What initially drawn you to the school? (Received brochures in the mail, know of the school from classmate, uncle is an alumnus, etc.)
*What majors does the school offer that is of interest to you? (You can generally see which majors players take in their bios).
*Take a good look at the school's website and read about the school's history, demographics, acceptance rate, etc.
*Have your latest transcript and board scores handy along with your spring baseball schedule.
*Review the current baseball roster. How do you see yourself fitting in? <Hard for me to tell not knowing your position> How many players do they carry? Looking at prior year "Stats" you will be able to see how much freshmen played and what position. You can also see which positions graduated. The baseball website also gives you an idea of win-loss record and schools scheduled.
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That being said you want to look at the facilities available for both off and on-season. Some indoor facilities are key for schools with severe winters. The coaches may give you an idea of their practice schedule (my son usually asked questions regarding balance of academics and sport schedule).
You can ask where the school is in recruiting for your class (if you don't know) and which positions they are actively recruiting. Any information you can gather on the school's timetable is beneficial.
Look up all the assistant coaches and HC on the website to see what they look like. Then rather than hi coach in a greeting, you would introduce yourself to Coach Brown, knowing by the picture. Son would talk to coaches about philosophy (does the coach play small ball, hit behind the runner, bunt, steal bases, rely heavy on pitching and defense, etc.)
Don't ask about scholarships at this point (maybe you meet financial aid on your tour). Coaches like to feel special and take pride in their schools. Whatever you can do to direct your interest in THIS SCHOOL vs just any college visit will certainly come across.
Good luck!