I am fortunate with my displays in that I live at the end of a cul-de-sac, so traffic isnt a problem. The most people we have had at one was 10 cars on Christmas Eve.
I love doing it, and I am doubling my christmas display this year. Unfortunately, as I am at college, I do not have the time available to do all of my Halloween decorations back home and my Parents and family don't have the time to match what I used to do.
It's a ton of fun though in the end, even after using my entire Thanksgiving break putting lights up and testing.