OKHaunting - your post was almost identical to my situation, all the way up to the <1 year-olds.
No kids at our party, period. The invitations state it and I have no problem telling people that it is "Adults Only and Costumes Mandatory". I tell them that if any of them show up in violation of either of these requirements, we'll close the door in their face... no matter the distance they've traveled. I'm not mean or rude about it. I'm just matter-of-fact, and those who know us, know that we'll do it. No one has tested us on either requirement yet. Actually, anyone who has made a comment to me about has said that they're relieved to have one night to themselves to hang out with friends. Both rules have become very popular especially with those who have no kids. Those who don't want to wear a costume, or don't want to come without their kids simply don't come... and we still had somewhere around 55 people last year. This year figures to be 65+.
Our age rule is if they're old enough to drive (16), they're old enough to drive their intoxicated parents home, so they're allowed.
My oldest brother is the only one that has asked to bring his kids, and he asked if they could stop by 1 hour before so the kids can see the decorations.
The reason I'm such a stickler on the age rule is because I don't want to spend the whole party entertaining kids, and I don't want my guests to have to do the same. I went
them to have a good time, not their kids. Also, almost every prop in my house is very breakable and I can't be chasing kids around the house making sure they're not touching anything. If the kids break a favorite, expensive prop, am I supposed ask to be reimbursed, or do I just resent those friends? If I don't allow kids, I don't have to worry about that decision.
We don't have kids yet, but when we do... they're outta here. We'll definitely be getting a sitter for our kids. Some of our friends think that once we have kids that we'll allow other kids, but they're
dead wrong.