Jan, I recommend the stick, too. Many dogs will back off if you do no more than raise the stick at them, thereby relieving the need to physically harm them. If they don't, you have to be prepared to use that stick. I see many people walking around with them, as you probably do, too.
I have the same problem that Denise mentioned. Other people will innocently allow their dogs to approach mine while I'm backing off and reeling in the leash. My JRT looks really cute and has the sweetest smile, but he is NOT friendly with other dogs until he gets to know them. So when they say, "don't worry, my big dog's friendly," I have to reply with, "mine isn't. please back away." Looks like the raised hackles and throaty growl would be enough, doesn't it?
Let us know how things progress!