Is it appropriate to invite high school coaches & school personnel to your high school graduation

I would think so. Coaches are definitely an important part of athletes lives. I don't know what you mean by school personnnel but I don't see why it would be inapproriate.

I too, think that it would be appropriate. Even though they will probably be there anyway, you would make them feel special because you have sent or given them an invitation.

comerw, did you mean to the full on graduation, or a party after the graduation? I don't see why you shouldn't be able to invite them, for goodness sakes they are the very people that helped you get there!:)
Congrats!