I've always had a method which makes perfect sense to me visually but is not easy to apply because people can have arguments over what counts. For some reason nobody agrees and I can't see why, it's so obvious to me.
The method goes like this:
If the spire is visually imposing such as on the tower below then it should count.
If it looks like a pole like on the NY Times tower then it shouldn't.
Simple.
Example:
The height will be up to half of its spire, exactly where it becomes pole like.