I've never been to one. As a kid, my mom's side of the family was always pretty close knit, at least as far as my grandparents and their 5 children go, and we would all be together for every Thanksgiving and Christmas.
On my dad's side, I've only really spent a whole lot of time with my grandparents. But they're both dead now. I can only imagine a family reunion on my dad's side would include a lot of political debate between my uncle and my dad (my dad is very left-wing for someone his age, and pretty outspoken about it; my uncle is a typical hardcore alt-right Trumpler, and pretty outspoken about it).