Like Grossie, we don’t designate wines as “special occasion” wines and will open anything, any day of the week. That said, I guess we do have a few bottles set aside for anniversaries and birthdays but those are more sentimental to us and not necessarily rare or expensive. My favorite person to share a special bottle with is my wife, but if it’s an offline than I think 4-6 is the perfect number to enjoy special bottles. With 4-6 you should be close enough to enjoy a nice conversation and everyone gets a good pour to take their time with. If it’s an offline that is about meeting people and having a relaxed time with good food and wine I say the more the merrier.