Answering this is little difficult as many theme or water parks have age restrictions. You are a well travelled person, hence you would know how important it is to know age of the child.
Suggesting some family friendly destination for Indians.
1) Malaysia ( KL, Getting , Mallacca, Penang)
2) Mauritius ( opt for good resort, as they have kids play area as well)
3) Dubai ( a mix of night life, water & theme parks & good hotels)
4) Taiwan (national parks & night life)
5) Phillipines ( beaches as well as night life in cities)
6) Hong kong ( Disneyland is the main attraction)
7) Swiss ( good clubs can be found majorly in Zurich & Geneva than in other cities). Also Swiss miniature is worth visiting.
You can plan a trip to Malaysia / Bali / Hong Kong
Dubai is also a great pick but it will be hot
I have written a detailed blog on my Top international pick for this summers where you can travel with Kids. You may pls read that for more suggestions.