Great. Thanks for the additional information. I really appreciate it.
It has been estimated that a jumping dog can generate as much force as a football linebacker taking down a quarterback. Even though your dog is being friendly by jumping on people, the fact is that the results can be the same...with the person on the recieving end of that jump hitting the ground...hard.
The first thing we need to do is to figure out why dogs jump in the first place. In canine communication, jumping and meeting another dog face-to-face is a common form of saying hello. If you've ever seen two dogs playing together, you'll notice that they act like a couple stallions, rearing up on their back legs and touching front paws as they play. Unfortunately, some dogs will transfer this behavior to their human counterparts in a ploy to get atttention.
We humans have a bad habit of accidentally encouraging unwanted behavior when our companions are puppies. It's super hard to say "NO" when your adorable 10 pound puppy stands on his rear feet and stretches up with his front paws to get us to pet them. But when we reach down to pet them during this behavior, it's accidentally encouraging this behavior, and although we smile and love it when they're tiny, it's less adorable when your pet reaches 70 pounds.
Since your dog is already jumping on people (and maybe even things like counters), we need to learn to break this habit by teaching your dog better behaviors. Start by teaching your dog to "Sit" and "Off". Using a Gentle Leader (www.gentleleader.com) and a longer leash. Have a friend or family member come into the house but to ignore the dog. When your dog gets geared up and starts running to jump on the person, give the leash a significant tug and say "OFF!" . Pulling on the leash will force your dog's head towards you and away from the person coming in the house It will make the dog unable to reach the other person.
As soon as your dog gives up trying to jump and sits, you need to issue a positive association...an immediate, "GOOD SIT!" and a nibble of tasty treat (I love using freeze dried beef liver...available at any petstore). Repeat this drill several times in a row so that your dog figures out that sitting, instead of jumping, brings about praise and something yummy. You can conduct this several times a week with different family members, friends, and even strangers (my poor mailman has helped me train many dogs) who might come to the house such as deliverymen so that your dog figures out that he has to sit politely, regardless of who comes in the house.
Once he has this figured out while on the leash, you can start training her the same way to sit in a specific spot (like a favorite rug or bed) when people come over. I'm sure your dog...like pretty much all dogs...is social, so we don't want to completely leave him out of greeting visitors to the house, but if you use the commands regularly, you'll be able to allow anyone to come into the house without worrying they're going to get knocked down.
I'd also suggest getting Parker into some obedience classes. Not because he needs to learn to sit and stay (although that's pretty awesome too), but because Parker sounds like a dog with some low self confidence. Taking him through the classes will help him build that back up, so he's less fearful of things in general.
I hope this helps.