Know Before You Go
Check for hours of operation before going. If you ask one of the security guards nicely, they just may agree to take you on a personal tour of areas where the movie was filmed that aren't open to the public.
If the mall doesn't entice you on its own, also in Monroeville is the Night of the Living Dead Museum. There you can find props, a miniature set of the mall, and actual pieces of the old escalators that were removed.
From there about 10-15 minutes down the road is Evans Cemetery, the site where the Night of the Living Dead series began. Look for the erect headstone that Barbara leaned on and watched as her brother was attacked by a zombie. It's just past the house on top of the hill, on the right-hand side.
The mall is obviously in a built-up part of town, but the museum and the Evans Cemetery is very urban-ish, much like a relaxing country drive.