These can be a blast! Used to throw them with a couple friends in another city. Here's how we did it:
The Party was open to couples and single women. We did not allow single men into the party. This kept the proper ratio and allowed for some girl-girl and threesome hookups as opposed to a bunch of guys standing around with their dicks in their hands hounding every available female. Everyone had to submit photos to make sure they met our criteria on attractiveness and height/weight proportions. And, everyone was screened. Entry fee was $100 per couple which covered all the food, drinks, etc. Payment by CC only. Single ladies attended free of charge.
We always had food, drinks, etc. for people to mingle. An "insider couple" was designated to kick the evening off to let everyone warm up. That couple would start having some sexy fun in a main room so people could watch and then the couple would split up ... the woman would select one man from the guests and start playing with him. The male would do the same. People were allowed to hookup as they pleased. Pair off and go in separate rooms or join in a larger group. On occasion, we would invite some form of entertainment ... couples who did a light S&M show, for instance.
We had a big bowl of condoms on the counter and everyone was encouraged to use them.
Professional ladies were welcome as guests, but it was understood that this was a private, personal night out. If they met new clients there, no problem.