If we were talking about a swimming pool, then sure, I would say excluding kids is just a petty grouchy thing to do. But for a lounge during happy hour? I don't have any problem with kid restrictions during happy hour. What is she to do? Sit and stare at the ceiling? I don't think so. She can enjoy a movie in the room and my wife and I will have a couple cocktails (and yeah, sometimes I leave my kid in the room alone, what a monster I am). As for breakfast, I don't see why kids should be disallowed, but if I get free breakfast at the restaurant instead, then I'd be more than happy to let the lounge exclude kids too.

As for airport lounges, I would have a problem with kid exclusions. My kid has a right to a comfy chair to read her book next to me just as much as an old grouch does.