It'll be FINE!
This is likely to get sweary as I have a rant coming on.
To those of you that say 'We love kids, bring them over, it'll be fine' when you don't really mean it.
1. It's customary to provide some food for guests if you invite them for a meal. If you know that what you eat and what they eat are very different, then either ask them to bring something to share, or buy in things they are likely to want. I'm not talking major expense here, but some bread and milk in the house when you have a kid coming for the day would be sensible and polite. OR tell the parents that you don't have those, could they bring some? Looking confused and then saying 'oh' is not the best response of a host asked if they have anything non-alcoholic for the child to drink.
2. Another thing that is normal, is to make some attempt to keep your guests entertained. You don't need to keep kids' toys around, but perhaps saying they can play the wii, then standing in front of them, talking loudly, so that they can't actually play, is a bit thoughtless. You are more considerate of your adult guests, why can't you be just as considerate to your younger ones? If the parents end up sitting with them in one corner of the room trying to corral them, it isn't much of a sociable occasion, really.
3. A kids' table is fine for the time that you're eating, fun, even. Unless there's only one child and no fucking food for them. Really?
4. I'm probably a bit old fashioned, but I did think that speaking to your guests was part of being a host. If there's someone trying to speak to you, but you're too pissed/loud/selfish to even notice them, you're being bloody rude.
Basically - if all you want to do is get pissed with your mates and not have to drive home - DON'T say 'bring the kids'. TELL PEOPLE that you intend to have a party for grown-ups. If you invite people who have kids, and say the kids can come, then treat them as if they are real-life human beings who have been invited into your house, and be polite. If actually you're too self absorbed to speak to anyone but your best mates, and you can't be arsed to include kids, but make them feel left out, then cut the crap, tell people you don't like kids, and let them plan appropriately.
I probably will judge you a little for being someone who thinks adults just spontaneously appear and you can't bring yourself to accept the existence of children. But I judge you a whole load more faking some kind of open-hearted welcoming shite, when really you make my child feel excluded and ingnored. It's rude and discriminatory. Your lack of empathy makes you look like a bully, and no, I won't be calling over with my child any time soon. Next time I'll hire a babysitter (who will actually talk to her and feed her) or better still, stay home, where the conversation is better.