Speedy - re the kids.
The best approach I've heard of came from another forumite, Candy Ollier. He is always encountering idiots, of all ages, and takes the "ignore them, they'll go away" approach to a brilliant extreme. He treats them simply as an obstacle that has to be passed. No eye contact, no attempt at humour, no defensive or aggressive behaviour on his part. Even if they're strung out across the pavement (goading him to react) he just runs around them. Just as he would a fallen tree or a patch of roadworks.
They're not people, they're not worthy of your attention. They are inanimate lumps of something unpleasant.