You are the same Paopei I know ?? From the pregnant team??
Chatuchak is really HOT... and stuffy. So, I recommend you go there at 9am, and leave by 11am..
For kids, there are some really nice items like :
Wall decor (cheap and cute for $0.20 Sin per pc)
And you can buy lots of hello kity accessories (storage box, baskets, giftset) at Chinatown :
Add : 856 Mungkorn Road, T.jakkawat (Sampeng) Sampantawong BKK 10100
Tel : 02-6224335
The boss is a Taiwanese chinese married to a Thai, she is super friendly, and the variety is a great! I am sure your darling would love their items!
Just tell taxi driver SAMPENG, and when you are there, ask around for the directions. Best to ask at the Lin ZHENG SIANG shops, they are real helpful!