I echo Dan's post and the others. Dogs are generally so deprived of getting to interact with their own specie, since they're so often leashed, that sometimes they just act like that because they want so badly to have some kind of relationship with other dogs. Some are definitely aggressive but sometimes it just looks like they are but they're really just very frustrated.
I don't usually like the idea of dog parks, but if you could find a friend or two who has friendly dogs and if you could all go on a walk together...walking parallel, with a purpose... without sniffing noses or coming face to face....and have some free playtime in a fenced area (provided they get along)....say, like a couple 2-3 times a week, that might relieve some of that frustration. Dogs need to socialize with one another. The more variety in dogs as playmates, the better.
You may have to be very active in searching out some people to help you, but that's where I'd start, in addition to trying to find a class where the trainer is willing to help you out. Be careful to find a trainer who isn't harsh. Yanking and punishing a pup for that behavior can make it worse as he begins to associate other dogs with a rotten time of punishment.
Like Dan said, teaching your pups to watch you and get their attention on you BEFORE they alert to another dog helps diffuse their excitabilty a little. But practice "watch me" at home.
You hold a treat up to your face and let the dog follow with his gaze. The second he looks up at you, treat and praise. After he does this a lot, start adding the words, "watch me" or "watch" or whatever you like. Then try giving the cue when the dog isn't paying a whole lot of attention to you, but is not too occupied with something else. If he doesn't look, you know it's not time yet to be asking for it ahead of time. Go back a step to where you show the dog the treat, he follows it up to your face with his eyes while you say, "watch" and you treat. Then go from there, adding a few mild distractions, little by little. Make sure the treat is something the dogs really, really love....even on a slightly hungry tummy helps.