Something educational. That is my goal all the time whenever I think of a gift to give to kids. They would love you for toys, and they would love you for something nice and educational as well. And you're loving them more with that because you are helping them more than making them happy.
Like this popular magic board that kids love. It benefits most their writing ability, their drawing ability and their imagination. I found this Megasketcher that erases on its own with little help only and the size of it is just enough for these art lover kids to be suffice for their limitless imaginations.
Give them the way to improvement of what they already have inside them. Give them what would guide them to what they could be when they grow up. Let them find where they will excel at and be happy at for their possible future endeavors.