Advice on Solstice Ritual
Raymond Arnold, a member of the LessWrong rationalist community in New York, was planning to scale up his "Secular Solstice" — a winter-holiday ceremony for non-religious people — from a small house gathering into a public, ticketed event for hundreds of attendees. Alyssa, who had helped run the Singularity Summits and other large rationalist-community events, sent over a checklist of practical advice.
I helped plan several of the Singularity Summits, the Humanity+ Caltech conference, and a bunch of other events in our community, so it might be helpful to run down the list.
Incorporate as a Delaware LLC — you're going to be dealing with serious money and serious contracts with suppliers, so you'll want to segregate the Solstice finances from your own personal finances. This can be done in about twenty minutes via legalzoom.com, or any number of other companies. This makes the company (and not you) responsible for debts, etc.
Set up bank accounts and accounting software for the LLC (I use QuickBooks Online). This is slightly annoying and will take about two hours, but it will save you so much trouble later it's not even funny. Knowing how much money you're spending on various categories is immensely valuable.
Set up a timeline, if you don't have one already. A December event means that you'll want to start selling tickets and promoting in September, which means you'll want to have the venue set up by August (venue is a requirement before you launch, because no one will buy tickets without knowing place and time).
Catering is going to be hella expensive, especially if you go for a higher level of service. For wrapped sandwiches that come in boxes, you might only pay $10 per person ($8,000 for a crowd of 800). For a formal cooked high-quality dinner with waiters and everything, of the type that (say) we had at a friend's wedding, you're looking at $50 per person ($40,000 for 800) and up.
Lots of venues (especially hotels and the like) will require you to use their labor for stage crew etc. as a condition of the contract. This labor will generally be unionized and will cost $200–400 an hour. Avoid this if you can, but it isn't always possible to.
You will of course need a website. Hell Design are friends of ours who will design one for you for something in the low thousands range. Volunteers are a possibility, since we know good design people, but this might turn out higher quality, might (more likely) turn out lower quality, and might (even more likely) simply never get done because the volunteer went off to play Minecraft. (Unless you know them quite well, expect at least half of volunteers to play Minecraft and not do what they said they would and forget to tell you.)
Promotion and marketing will likely be the hardest part of the event. At this scale, expect to do a lot of "hitting the pavement" yourself — have postcards, pamphlets, etc. made (99designs.com, printingforless.com) and then hike around New York City giving talks, going to meetups, networking at relevant conferences, etc. and passing them out. (Order thousands of them — economies of scale mean that it's only slightly more expensive than ordering hundreds.)
The media, when they write about you, can only put you into a small number of possible "boxes". Pick a box that you'd like to be in, and plan accordingly. Be sure that it isn't "brainwash chanting by doomsday cult".
If you need help with logistics, organizing, or finding lots of cheap labor, Ben Walker [email redacted] will take care of everything for you for a reasonable fee. His motto is "no problem too strange".
Amy Willey [email redacted] also helped run a lot of the Summits and might be happy to give you advice on various matters.
For an 800-person event, make the afterparty small; the new Brooklyn house is probably of sufficient size and is a suitably private place, although it may not be viable if it's too far from the venue. Handpick people and personally invite them. When people buy tickets, ask for their employer and job title (not income, though, that's crass). Use my techniques at How to Find Anyone to research people and decide if they're worth inviting. Resist the temptation to include everyone and recruit everyone; remember that coordination costs scale non-linearly with group size and that larger groups get their mission diluted in proportion to their largeness. The upper bound for the entire save-the-world group is probably around a few tens of thousands (as large as science in 1900, or Google today).
Have a high initial price, and then give discounts at the drop of a hat. People like discounts and it gives you an excuse to talk about the event on blogs, mailing lists, etc. Over a few months, find hundreds of cool people on the Internet and cold-email them to invite them for free. A conference has high fixed costs but low marginal costs — organizing and renting the venue are expensive, but the additional cost of filling another seat is low.
If you want people to "join a community or organization", be very very clear on what this is, what it does, why people will join it, and the path for them to do so. There is a tendency among transhumanists (even more pronounced among effective altruists) for everyone to start their own organization and for them to all then bicker with each other. There's also a tendency for organizations to get dragged down by internal political battles (Humanity+, Extropy, IEET, Lifeboat) or become popularized into meaninglessness ("Singularity", "nanotechnology", etc.). There's also a tendency to try to "recruit" anyone and everyone, without a clear idea of how all these people will be organized or what they will all do, and there's a tendency to "recruit" people to Pascal's Mug them. Avoid these failure modes.
I'm sure I've forgotten a whole bunch of stuff, but we'll remember it later. Good luck!