Rule of thumb: 8–14 seats
Too small and it's insider-y. Too big and it's a networking event. 8–14 is the magic range for actual conversation.
Gate on a specific collection
Don't gate on "any NFT" — that dilutes signal. Gate on the specific collection you're building around. If you have multiple, use AND logic.
Add a POAP as the memento
Everyone walks away with an on-chain souvenir. Increases attendance at the next dinner.
Charge a small deposit
Even a $50 refundable deposit dramatically reduces flakes. Stripe or crypto both work on IRLEvents.