Well the champagne brunch at Mezza9 (Hyatt) is fantastic. As long as the kids are pretty well behaved I can't see them being a problem. If there are enough of you, then you could try and get one of the private rooms.
They even have a chocolate fountain which kids love (OK and adults too) THe only downside I can see is that you will imbibe so much champagne that you might well forget that you brought the kids with you and leave without them
