I've got a kid one level past that, single A, where they start having umps. They're all 13 and 14. And believe me, some people can't help themselves and just have to say crap loud enough for the umpires to hear. I always give a little "good job blue" or something like that during or after the game even if they suck... because even then, it's 9 year olds for goodness sake.
My wife and I always try to say thanks to the coaches after a game. I get frustrated enough trying to get my own kids to pay attention, let alone ten other kids that aren't mine. I really do appreciate their patience and willingness to spend their time doing that stuff, because God knows I won't do it.
I think that after this last round of baseball we'll be out of the youth sports game for a while. My son doesn't much care for any sport he's tried so far and my daughter is only two so I'm likely getting at least a brief break from the craziness.