Shelley,
I can relate to your frustration. Whereas, 4 of my dogs are friendly to other dogs and love to play, Shiloh is a menace. When he sees a dog no matter how far away, he goes ballistic! He wasn't always that way though.
I don't think obedience class will do you any good, most trainers only do the clicker training/rewards training to teach your dog how to sit, stay, down .... they usually do not address behaviour modification and quite frankly, many of them don't have the skills that are required for that. What you would need is a dog behaviorist.
A book that I would highly recommend is Eileen Tonick's "All dogs are angels at heart" Here is the link
http://www.authorhouse.com/BookStore/ItemDetail~bookid~47827.aspx
Let me know if they cannot ship to Canada and I will get it for you and mail it. Eileen actually is my dogs' agility trainer. Whereas I am also a certified dog trainer, I hired her when I was at my wits' end with Shiloh.
You mentioned in your post that you use one of those halties that attach to the collar, the problem with most regular collars is that they sit too low on the neck which makes corrections very ineffective and sometimes even dangerous (the dog's trachea could easily get hurt because the dog keeps pulling and pulling when they get excited). The best training aids are the ones that stay very high on the dog's neck, right behind their ears. It makes it almost impossible for the dog to pull, jump up and down, etc. because the collar is on the neck where the dog's pressure points are.
So, on the gentle leader, I would look for something like this
http://www.edogsncats.com/html/gentleleaderfull.htm?gclid=CITBi4vN55ICFRwqagodXTy14Q
This is what I am using with Shiloh and really hard to train, excitable dogs. It's sometimes called the "10-minute attitude adjuster". Don't get me wrong, most dogs will fight it in the beginning and turn into a bucking horse for a while
. Just keep walking and ignore the behavior, your dog WILL follow.
The other one is actually a show collar, when you see dogs at dog shows they always walk or trot upright, paying attention to their handler. It's not the dog necessarily being well trained, it is the collar. It forces their head up because again, it sits right behind their ears and targets the dog's pressure point.
http://www.ryanspet.com/ryanspet/productList.asp?categoryCode=283&startItemCnt=1
These are not regular choke collars, they are much thinner which makes it much easier to give quick correction, because they move easily through that loop and again it targets the pressure points of the dog. Be careful not to jank too hard on it though, a quick pull is enough to get their attention without injury.
I was training a dog that almost pulled the owner's arm out of the socket every time she was walking her. After 30 minutes of corrections with that collar my 8-year-old son was able to walk the dog without problems.
With your dogs both going ballistic, it is also pack mentality kicking in, one starts it and the other one joins in. As it was said before, it might be better to take them separately for walks, at least until you get that problem under control. You have to correct the dog immediately when she starts her behavior and it is hard to do with two at the same time.
So, what you do whenever your dog exhibits unwanted behavior, like the barking or lunging at other dogs, immediately give a quick pull on the leash and/or snap your finger and point at her and say in a very firm voice "No", "Ahah", "Hey" or whatever word you want to use. It doesn't matter what you say, it is the energy you project.
If she still keeps going, move right in front of her and walk towards her, blocking her, basically hovering over her, keep the leash tight until she sits, rolls on her back or otherwise submits to you. If that still doesn't work and she keeps barking, or barks again walk her away from the situation, getting her mind off and focus on you.
You just have to be very consistent with that, she will eventually understand but it is not going to happen overnight.
As to why your dogs are doing it, I have no idea. Different dogs have different boundaries, some dogs will let other dogs almost step on them without doing anything and other dogs, like Shiloh have boundaries that when they see another dog 1 mile away, they go ballistic. Those boundaries can change based on events in their life, in Shiloh's case, he was attacked a few times and he panicks, starts barking, shushing them away. Aside from fear it could be that your dogs are overly excited, don't get enough exercise, are not challenged enough, have taken over the leadership from you and see themselves now as the alpha-dog defending the pack, or .... you probably are the better judge of that.
Whatever the reason is, you have to make it clear to them that you are the one in charge and that their behavior is unacceptable. If you keep going like that it WILL get worse. There is something called negative programming, if you keep letting them get away with it, they think it is okay, actually what is expected from them and taking over leadership more and more.
With Shiloh it got so bad that he negatively effected the basically calm/submissive structure of my pack and they started turning on each other, with very serious dog fights amongst them, all 5 of them going at each other. Not a pretty picture!!
I am working with Shiloh every day and there are small victories, like today he let a pitbull puppy get close to him (which is major because both serious attacks that triggered his behavior were pitbulls) and he even rolled over and let her sniff him for a couple of minutes before he all over sudden turned AGAIN, and then there are setbacks, lots of them. But I keep exposing him to other dogs in a controlled environment to slowly increase his boundaries. It's a long way ahead.
Don't feel bad, stuff like that happens, even with all I know about dogs, I allowed Shiloh's issues get out of hand. It's just a matter of regrouping and (re)claiming your status as the pack leader. After all, who is the one who is putting food in their bowls
.
I know it is embarrassing, annoying, frustrating ...... But don't give up on them. The beautiful thing about dogs is, they live in the moment what happened yesterday or what happens tomorrow doesn't matter to them.
Sorry this was so long-winded, I hope it helps.