LOL, Sokka and Katara aren't necessarily 'Native American'. They're most likely Inuit, which is similar but not the same (more Asian influence). Anyway, I don't know very many Native American actors/actresses (although I think Kristen Kreuk is part native Canadian, I'm not sure). Regardless, casting an Inuit character as Asian is better than casting them white, in my opinion. *shrug*

I was also typing this up at work, and didn't have a whole lot of time to search for the perfect picks, just picks I thought were better than Shyamalan's. If I found two Inuit/NA actors who matched Sokka and Katara, I'd select them in an instant.