Oh, yeah, the parents always stay down here. Not sure if it is an all-American thing or a South Florida thing, but even if you have it at your house, the parents stay. Will had his first one at three, at Gymboree. I wouldn't have even done that, but his little best friend's birthday was around the same time, all their friends were in common (from the neighborhood), and the friend's mother split the cost with me.
Here's a picture of him and me at that party. He was having "Happy Birthday" sung to him, but apparently his mind was elsewhere. What can you expect for a three-year-old boy?
That went so well, we're doing it again this year. They're both in pre-K and in small classes, so the kids are from school mostly, plus one or two of the old neighborhood gang. (We didn't do it last year because Will had to have hernia surgery right around this time of year, unfortunately, so we just did a little get-together with a few friends here at home - turns out it followed your rule, Anke.)
Katherine, the thought of having a bunch of six-year-olds at my house is terrifying to me, too! Especially since down here, their parents would be staying, so I'd have to have food and decorations that please them, as well.
The party today is almost more about the adults. We ordered little ice cream cakes (good call!) for Will and his birthday partner, but since it's at 3:00, we didn't order pizza for them. Instead, we're bringing nibblies for them to grab periodically while they're playing (and really more for the adults - his friend's mom is making her "famous" spinach-artichoke dip and salsa this morning, and I'm making a chili-cheese dip that's cooking in the Crock Pot right now). We keep finding as we go to these things that the kids really don't want to take a break from playing for long, even at lunch time, so the pizza goes to waste and you end up feeding them again at home, anyway. But of course, now that we geared it more towards the adults (there are going to be about 25 - ugh), we're ending up doing more work than had we just gone the usual route. Oh, well. I don't get out much anymore, and I don't have dinner parties so much as I used to - everyone with kids and other obligations, now - so what the heck.