Thanks @riverflows. So as I mentioned above I think one idea that could work across all tribes is embedding your discord channel in the tribe site. This would allow people to "hang out" on your site even if they're not posting at that moment.

I think another thing that could help is a featured page where the owners/founders could hand pick some of the best content and have that be the first thing people see. Those are sort of generic ideas as I don't personally know much about that content specifically.