Hai Maya,
This is what going in the minds of every parents when it comes on saturday and sunday or in weekdays evening..............
But there are places in chennai, which many of us doesn't know. I will list out some places which i know.........check it out.......
1) Guindy Childrens park - cheap and best
2) A new park opened opposite to Ashok pillar hot chips. (like this there are many parks opened in most of the areas in chennai)
3) Vanilla Place - check their website
Vanilla check with the below link also where v discussed about this place
Vanilla Place - In Chennai
4) Abirami Mega mall - child area - but not much place inside to spend, costs Rs. 70 for children and Rs. 40 for adults (correct me if i am wrong) and that is only for 1 hour.
5) Vandaloor Zoo
6) Now u have our Trade Fair in Island grounds - cheap and best.
7) Beach - cheap and best
i will cum up with some more.