I think this is a very broad question/statement. What exactly do you mean by 'ideal societies'? That is, what is you definition of an 'ideal' society? 'Ideal' in terms of exactly what?
Modern ideal societies show a cultural, liberal growth as well. These societies put an increasing emphasis on equality and education for everyone as seen in the wide-reaching civil rights movements. Economic opportunity allows people to create wealth for themselves and society, while quality of life allows people to enjoy their wealth. . The characteristics of successful ancient societies/civilizations are: Mutual respect, Tolerance of harmless differences, Intolerance of harmful elements, Punctuality Kindness towards all, Honesty, Cleanliness. Code of Honor, Family integrity, Obedience towards authority.
1.The idea of ideal society leads to perfection and the idea of human nature is to make mistakes. Hence societies with humans to create a harmony among one another will always remain as a fantasy. But to consider the impact of AI in todays modern era, ideal society might be possible.
2. Ideal society doesn't always have the idea that to represents a state or a country. It can also refer to like minded people who gather to address an advancement or to achieve something to create larger impact. In this case you can find all the qualities mentioned by Kiran Grover in the above reply.
These gathering will be mostly identified as Secret societies.
One person's utopia may be another person's dystopia. This is reflected in the different attitudes held towards to the nature of the allegedly utopian "heavenly" afterlife propounded by various religions.
“The dog is a gentleman; I hope to go to his heaven not man's.” ― Mark Twain
The ideal society in the modern context is the best one that coexists with the differences between groups and privileges individual rights without despising the majority.
I don't see a modern society mature enough to be considered an example of idea sociology.
I hope I understood the question and answered it in a satisfactory way.