While not being a carefully gaurded secret....
If you are there on your birthday - or your kids birthday... stop in at city hall and get a birthday button. We did this for my daughter, who turned 6 last November. She wore it all day, getting many well wishes along the way. She was singled out during the day parade, and every character signed her autograph book with a nice big Happy Birthday wish.
To top it all off... at the Plaza eatery, they gave her a free ice cream bar for her birthday just before the electrical parade.
It made the day even more special.
BTW - we go to the parks about two or three times a month, and my daughter still finds the magic, thanks to little things like this.