I've already found using DO13 and it's extension filter that it would be nice to be able to include directories along with selected extensions.
Do you mean on the Filter Bar? You can click the file and folder icons, next to the counts on the left, to show/hide all files/dirs.
I'm talking about the filter, on the filter bar, that allows you to show just specific file extensions like (.mov, .txt, .exe, etc). I'd like to be able to click on Directory just like I would anything other extension or file type group to show me just the directories. I'm not sure that it has value doing it in combination with an extension or a file type group like videos or something but as it's own entity it would be nice to hide all the files and show just the directories (especially in folder formats that mix files and folders.
You can do that already, via the method I mentioned.