My dog uses his mouth to "touch"...?

I have a pit/shepherd/beagle mix who is a little over a year old now. He is a great dog, very loving and obedient. The only problem I have is when he's excited he will use his mouth to "touch". He doesn't bite at all, but will put his open mouth around a hand or arm (or whatever part of another person or animal) to "touch" them. I've attempted the whole muzzling his mouth shut with my hand as I say no into his eyes. I've even attempted some of Cesar's (the dog whisperer) tactics--ie. "biting" him with my hand (as a pack leader will do to a lesser ranking dog to reprimand) and even completely ignoring him while he's exerting this bad behavior. Everything I do seems to my dog as a game and he just gets worse with it at the time. What do I do?? Also, I will not crate him for this.