This year I did a small "Darkness Solstice" in the woods (i.e. basically got up to the moment of darkness, and then instead of having an uplifting third act we just sorta sat in the darkness for awhile).
"Darkness Solstice" probably doesn't make sense for most people. But a thing that was interesting and perhaps surprisingly relevant was "Solstice Quaker Circling".
After the moment of darkness we just sat around a campfire in silence. Anyone could speak up and share something if they felt like it. I modeled this after the structure of a Quaker meeting, with a vague dose of Circling culture thrown in.
When you felt like you'd had "enough", you lit a candle indicate you were ready to move on from the segment (which in this case meant wrapping up the solstice with one final song)
I think it was about 40 minutes before a critical mass of people had lit their "I'm done" candles. I was happy with how the "I'm done" mechanic played out – if I had had to guess how long to have the period have lasted, I might have went with something much shorter.
We ended up sharing a lot of personal stuff that felt valuable to me. There were some impromptu solstice speeches came up that were interesting. Some minor personal interactions.
A question came up: "Am I allowed to respond to what other people have said?" and my answer was "Yes, but only in slow motion. To preserve the overall vibe and prevent it from turning into "just a conversation", the guideline was to always wait a minute or so before saying the next thing. So, you could respond to something someone else said but not transition into rapid back-and-forth that'd have killed the mood.
It as definitely a great experience for me as a small solstice. There were six of us there, and five of us shared things during the period.
I think this might surprisingly just.... work, even at larger scales? Its modeled after a Quaker meeting. I've seen Quaker meetings work well with ~30-40 people, and the largest ones are apparently ~70 (but maybe have a different vibe than the smaller ones).
In open-invite large scale Solstice, I think there are additional complications – I think it's bad to create an illusion of a safer space than you can guarantee. There's also a risk of someone bringing up a social conflict in the middle of the space, or a political rant, in a way that's hard to deal with. (It seems to me the Quakers would also run into this problem at least sometimes. I'm curious how they deal)
I tried this out specifically hoping it could be a thing that worked well at small solstices, and gave people more of a reason to hold private events after they go to Big Regional Solstice. I think it worked really well for that.