I'm a novelist who teaches novel-writing on the side. I have a long list of "how-to" classes on fiction writing -- small stuff like world-building, plotting, and character development, big stuff like "How to Write a Novel" and a pathway through the biggest destroyer of novelists, "How to Revise Your Novel."
So my forum is a mix of general-membership shop talk and goofing around, purpose-built forums for specific classes (with questions and answers), private space for me to talk with my moderators, privater space for individual folks to talk directly to just me. I'm using every single option XenForo offers for one or more tasks.
It's a closed community. To reach the forums, folks have to be site members who own one of my writing classes.
I offer one free class that confers general membership -- How to Write Flash Fiction That Doesn't SUCK. It's a popular class, with a lot of folks who use it to make their first fiction sales. So I have a LOT of free members.
Having that free class makes sure that ALL members have access to the general discussion boards, to the "bought a class on Amazon" boards, and to a couple fun things we have there just because. Most discussions take place in the General Forums, because they're busy, they're fun, and everyone has access to everything being taught in the classes linked there.
I also have a number of small classes up on Amazon, and folks who buy those get free membership, the worksheets, and the related forums.) So along with free membership, there's "under ten bucks" membership. And they, too, use the General forums.
Private forums are for the big, expensive classes, where we're doing active research on expanding our fiction writing skills, our readerships, improving our marketing, making sure we master titles, covers, copy, genres... Bunch of stuff. Fiction writing is a highly technical craft with a helluva lot of moving parts if you want to succeed and make a living at it. And at the top end, the folks aren't there to see their names on books. They're there to build readerships and do this as their real jobs.
So I use private-access features, too -- one-to-one match-ups between owning a class and reaching a forum, and I need to make sure that folks who drop out of those classes have forum access shut off. (And that if they come back later, which a lot of my guys do) forum access re-opens.
Finally, the site is fiction writers only, the topics are fiction-writing related, and because this was not my first rodeo and I learned from my mistakes, the TOS includes my "no politics, no religion, no personal attacks, no flames" clause for forum use, and in the last fifteen or so years, I've had to kick out one member, and block one from forum use, both for violation of terms of service.
So I've also used the ban feature. Twice. So I have to have it.
Two people total out of the thousands of members (and the hundreds of active forum users) is not too bad, though.