If your good with posting Google Map links you could use that. Say your event was at the White House, but you didn't want to give the address. You could give this link https://www.google.com/maps/place/38%C2%B053'55.6%22N+77%C2%B002'11.9%22W/@38.898765,-77.0371962,217m/data=!3m2!1e3!4b1!4m6!3m5!1s0x0:0x0!7e2!8m2!3d38.8987645!4d-77.036649 It will put a pin where ever you have selected and allow you to get directions to that location. To do that just click on the map where ever you want the pin to be and at the bottom of the screen you get a small card to pop up, then click the GPS coordinates and it will center the screen there. Then you can use the URL and make it a hyperlink where ever you post it online. For flyers and posters I would give the closest address, I don't think you would get a good response with GPS coordinates (unless its that kind of event).