If you have never been, and it is free, I think as a theme park aficionado it would it would be a great experience to see a new Halloween Event at one of the Busch Parks. While it's not HHNs it is great event along with Howl-O-Scream in Williamsburg.
We all know what HHNs is all about, but I am interested to see how you would compare Halloween Horror Nights, Howl-O-Scream, and Knott's Scary Farms.