I do think this is a good idea, in the UK there are already adult only hotels, and some restaurants do not allow young children, then of course some licensed properties cannot have children enter either. If you can access child friendly places, then why can't we as adults access adult friendly places?
I do think it would be a good idea to have a separate area on aeroplanes, especially on longer flights when young children are likely to become bored, and so whether they have good parents are not, they are likely to misbehave. The last time I was on an aeroplane I had the joy of a child (about three) kicking the back of my seat the whole way home on a night flight, while mum and dad had ear plugs in, eye masks on and decided to go to sleep and ignore her! If I could choose to be in a none child area of an aeroplane I would, just as if I were to take young children on a flight I would choose to sit in the child friendly area out of respect for other passengers.
I must admit I see very few parents being responsible in public, of course all children cry etc, but it isn't necessarily the behaviour of the child, it is the reaction of the parent, I have been in restaurants with children running around, I have been somewhere where this has lead to the child running into a waitress carrying food, so not only is that a safety issue, but also that is money lost as the meal has to be made again, and the customer has the inconvenience of waiting longer. I also think establishments have a duty as well, if a child is running around I think the family should be asked to leave, if you're in a restaurant the only time you shouldn't be seated is when you are going to the toilet, sadly due to many parents being no less than abusive when their parenting is put into question many people are now too scared to tackle problem children.
I used to work in a shop and children were often a nightmare, many were left to just run around the shop, yet if they had hurt themselves on something their parents would have immediately blamed us, or their would be the typical parent who can't really be bothered, so they would just be screaming the child's name, because walking ten metres to punish your child is just sooo much effort. Most parents would also allow their children to completely trash the children's magazine section, so in the end it would turn into one massive pile, then after much begging they would buy them some sweets and then let them discard the wrapper either inside the shop, or outside, so either way we still had to clean it up.
I love the idea of child free hotels, I'm going on holiday soon and we will be avoiding anywhere with the words "child friendly" or "kids club" I want to relax by the pool, not listen to squealing while I get soaked by children jumping into the pool, I also don't want children running around me while I'm on the beach, I don't want to be completely smothered in sand.
As children my sister and I did not misbehave in public, we knew not to, and at that time it was very rare to see children misbehaving in public, yet now parents seem to believe it is normal, and they say "oh, they're just kids" no, they just have no boundaries or respect. My nephew for example, he is a lovely child, however he is allowed to get his own way, so if he throws a tantrum while out he is bought a toy, because his parents would rather do that than actually tackle the issues they have created.
Parenting has become so bad in the UK that children are starting school (age 4) who aren't toiled trained and who cannot even use a knife and fork! If there are parents out there who consider this too much effort, it isn't a shock that we do have so many ill behaved children around.