Ken Watanabe is a popular fan-cast for Dalinar, both by Reddit and a Tor blog post from a while back.
At a release event I remember Brandon saying he once went through a book of headshots just to get a clearer real-life image of Kaladin in his head, and the model he felt was closest had very mixed ethnic ancestry. But essentially the Alethi look like an amalgamation of everything between, and including, Egypt and Korea.