Buy refundable tickets (e.g., Southwest).
Don't feel bad if you get an offer from school #1 (which you are convinced will be honored by admissions) and call off further visits - the players assigned to care for your son wont mind the all-of-a-sudden free weekend.
Coaches understand how the recruiting game of musical chairs goes and flows; you are simply protecting and hedging your interests.
Exciting times - when it's over and you look back, the sigh of relief/satisfaction is priceless.