If you’re from out of town, the minhag hamokom is to be polite and say something to show the other person that you recignize him as a tzelem elokim. For some reason, in more in-town places (Brooklyn, Monsey and even the new Lakewood), the minhag hamakom is different.
Whenever I travel to these places, I say “Good Morning” and “Gut Shabbos” to everyone just to see the reaction. Usually it’s just a double take, like,”Do I know you?”