I have two WP + Discourse projects to share 
Cracking the Code
Guitar learning site, and member community, focused on helping players improve their technique. This has been my day job for several years, and after offering downloads + subscription on a third-party platform for a while in the past ~2 years we went all in with our own custom site integrating the lesson material and community forum.
Wordpress:
Discourse:
Antilibraries
Site where I curate and share the most fascinating books I find, and associated forum for talking about reading and libraries, trading book suggestions, and similar. I’ve been working on the general idea as a side project for a while, and just a few months ago launched a small forum to work more on connecting with a community of like-minded book nerds.
Wordpress:
Discourse: