Thanks, this had been recommended to me by our IT guy, but while it told me folder size, it didn't allow me to filter as I ultimately wanted to. For example:

Folder size for all subfolders containing "Photos" in the folder name, with contents from at least two years ago. Power Query gave me results I could filter to get this.

For other purposes windirstat would absolutely have done the job. They at least identify where the bigger stuff is. But with PQ I could further drill to stuff I could actually do anything about. One of my projects is taking caches of old photos and batch-reducing the file sizes of said photos. It's good busywork between other things.