Sex. Feminism. BDSM. And some very, very naughty words.
We had regular date night schedules, which alternated houses based on where we were playing D&D. Lately, our schedule hasn't changed in 3-4 years, we're like old sedate polyfolk:)
Joe-- and they say D&D will never get you laid...
It's helps if you've settled into a long-term routine and have reasonably compatible schedules, etc. Typically, the other 40% of the family shows up every other Friday and leaves Sunday night, with the occasional longer weekend, holiday, family vacation, etc., as well. Our erasable yearly planner is more to juggle work/school/nonpoly social stuff than it is for poly. Of course, we're pretty boring, vanilla polyfolk.
@Joe:Man, wish MY campaign worked that way!
You know they always say it's not good when the DM gets his girlfriend to play. But when it's his wives and husbands and their lovers, it sort of works out;)