Addams is going to be insanely expensive because they have to get the music licenses PLUS likeness rights for every actor on the backglass PLUS dialogue rights for all the sound samples. It would be very, very difficult.
With Twilight Zone, all you gotta do is get the base license + music + likeness rights from Rod Serling's estate.
Since they are using works written by people other than Rod Serling, and also using images of actors (like the Hitchhiker) wouldn't they need to spread some of that around? Maybe even to CBS if they picked up the rights to the words and images, I dunno.