I took my two kids (3 yr old and 11m) to Thailand last week.
The most important thing is water and medicine, esp. if your child is allergic to some food.
May need to take some bread (can buy in local bakery), snacks, e,g.biscuits, baby food, as some thai food, if eat in thai restaurant, will be too hot for small child.
I find a ckecklist for things to take if travel with small kids in another discussion thread, which is very useful in packing luggages.
I will go with my son (almost 3 years old) to Bangkok this Friday. If just eat 泰式魚蛋河/日式烏冬, it would be too bored for him. Any mum has experience or can suggest some restaurants for me???
When I take my son to bangkok (less than 1 year old), I stayed at the apartment. I bring some rice and 字母粉 to cook for him. you can buy some fresh food from supermarket. I also bring a 真空杯 to go! it's very convenience!!!
I brought some bread/biscuits (can buy in local decent bakeries in big dept.store) as snacks. If I dined in Thai restaurants, as food were too hot for small children, I'd order white rice and some pork (not so spicy ones) and add some bread for my elder son. I'd then find some restaurants with other cuisines: e.g. the Jap one: Shintaro in Four Seasons Hotel is great, can order Udon. French ones, to order pastas, try some high teas in hotels/big shopping malls, to order cakes. Chinese food in China Town. Fruits in supermarkets, etc.
For small babies, better take baby food and drink one more time of milk in the day la.