I think it would depend on a couple of things. 1) What kind of holiday you want to have with your son - a theme park type fun or a cultural type fun & 2) What type of things is your son interested in?
I know my kids would be bored out of their brains, but my friends kids would get great enjoyment from the adventure & culture, even though they are young.
Probably the best thing to do would be to look into what you would do in these countries & also what is available there then decide if you think your son would have an enjoyable holiday because the last thing you want is him being bored & whingy all the time as it will ruin the holiday for you too.
As for the countries being appropriate, I have only been to Thailand (in asia anyway) & I think so long as you are cautious & aware of any risks before you go, then there should be no reason not to take children to these countries. I believe if all children were given opportunities such as this they would all grow up more tolerant of each other & appreciative of what they have in their lives..
Good luck, I hope you have a wonderful experience wherever you decide to go