I think we have a pretty utilitarian view of Slack. We have a small team of 6 that's all eager to get work done. Slack helps us stay productive/efficient/communicative.
So what I mean is...we don't have a lot of fun/hangout channels. The only channels that qualifies as those categories are #love and #random -- but #love is all about work (sharing awesome DEV things we find in the wild -- i.e. your laptop sticker makes us 😍) and #random can sometimes be random, but generally lands peripherally work-related (i.e. Whoa, WeWork just purchased Meetup!).
Channels that help us communicate are pretty self-explanatory: #team (something everyone should know), #dev, #creative-marketing, #office.
We also use Slack to get one-way notifications, such as: #deployment-pipeline and #bug-reports.
We probably have more archived slack channels than active ones and we'll continue to do that. I think it's the worst when inactive channels linger around. For example, we had a #video channel when we did a lot of video editing --- we'll likely revive it as we go into season two of BaseCS ;), but for now, it's not serving a purpose and anything video-related can go in creative-marketing.
Just keeps things cleaner/easier.
Moral of the story: be archive-happy.
I also wrote a post on how I personally manage slack:
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.