I have a 5 year old Lab. As a puppy, I took him through a few of the basic behavior/obedience courses. He learned the basics, and still follows them fairly well to this day (sometimes with a little stubborness).
When it's just me, my wife and the dog, he is very sweet, calm and obedient. He is playful when it's time to play and is content chewing a bone in the living room when my wife and I are otherwise occupied. He follows his commands well when it's time to eat, go outside, go to bed, etc.
The problem is when we have visitors. As soon as a guest arrives at the door, he flies into a frenzy and most commands are ignored without reward. I can get him to sit and stay for a moment or two at a distance from the door, but he barks loudly and you can see all his muscles twitching in excitement. Once I get near the door, he leaves his spot and comes running, panting, barking, bouncing in circles and throwing his body into the guests' legs. Once I finally spearate him from the guests he torments everyone by jumping, barking, stealing shoes and items from purses/bags/coat pockets, humping small children and stealing their toys from the time they walk in the door until the time they leave. Each time an event like this occurs, I stop what I'm doing and try to tell him that what he is doing is bad. I don't physically hit him, but I stop him from what he's doing or take the stolen item away and tell him "no" (a command that he normally listens to when we're all alone). If I make him go in the other room and stay, he barks uncontrollably to the point where it's not enjoyable for anyone. I should note that none of this behavior is violent. It's all very playful, but being almost 80lbs, it's not fun for anyone.
Once the guests leave, he returns to his bone in the living room like nothing happened and life is back to normal.
One thing that is different when we have guests is that he does get certain treats when we have company. This has always been the case, even as a puppy, simply to give him something to do since we aren't giving him attention, but in the last year or so he ignores the treats and focuses all his attention on the company.
I apologize in advance for the lengthy post, but I'm at my wits end here. Can anyone give me any advice.