We've seen two or three coyotes here (NW shitcago burbs). They've gone after the dogs of a couple of idiots who leave them tied out but so far the hysterical barking has brought the owners out before the coyotes actually attacked. I chased them away from a beagle once. Idiot owner left the dog tied out and left the house...
I've also seen them at the neighboring park. So far they have not directly approached me and the dog (55 pound Border/Lab mix) though they ran by fast and a little too close once. They don't like a real bright flashlight in their eyes (and they also don't like a strobing LED flashlight in their eyes). That works on skunks too (which are more prevalent than ever)