I am a certified dog trainer and I strongly encourage you to train your dogs. I would be very wary of the dog whisperer though. There are far more effective techniques that are not dangerous and don't require you to be aggressive toward your dogs. Look for a dog trainer who uses positive methods (if the trainer talks about using a choke or prong collar or another device other than a soft leash to control your dog, find another trainer).
You are right, the dogs are part of your family, but you wouldn't allow anyone in your family to behave aggressively toward guests, so why should you allow your dogs to do so? They need a time out, just like you would for your children. If they start barking, put them in the other room and don't let them out until they settle down. Once they are settled, you can let them out to go and calmly greet the guest (You may need to do this one by one to accomplish calmly).
Just like with kids, you need to be consistent. Every time they freak out and start barking, put them in a room until they calm down, then give them the positive reinforcement of letting them go greet the guest. The one time you let them get away with barking you erase the rest of your work. You could practice this technique by having your kids go and randomly ring the doorbell throughout the day.
Regarding Caesar Milan, here is a review that a dog trainer wrote that I completely agree with:
"People tend to forget that Cesar is dealing with behavior, NOT training. He is trying to eliminate old problems, and that sometimes require force, but should ONLY be done by a professional and can take anywhere from a few days to a few YEARS to completely fix. [Sometimes force itself can make the problem far worse!]
The training technique that a majority of dog owners in the United States (and other countries) should be using is positive reinforcement training. This is a reward based method that does not involve ANY physical punishment. BUT positive reinforcement DOES still involve punishment [just not physical, more like the removal of reward, etc].
Cesar often uses techniques that would be downright dangerous if anyone but a professional (or perhaps, someone who wasn't in front of the camera) attempted them.
I do like the fact that Cesar stresses that there are no bad dogs- only bad dog owners. While I believe this to be very true, I find that he sometimes fails to explain exactly how to be a good dog owner. He describes how one can fix a problem- but not how one can prevent it.
One of the biggest problems I have with him occurs during one of his episodes. There are blurbs that appear before EVERY episode that say "Do not attempt these yourself- please consult a professional, etc. etc."