I totally agree with alot of people saying that Liev Schrieber should replay his role as John Clark. He was perfect. Plus it would be nice to see some other consistancy with the characters (ie Harrison Ford as Jack Ryan). Allthough, after seeing his role in Tears of the Sun, I think Bruce Willis has the potential (under the right direction) to be a great John Clark.
As far as Ding goes, Oded Fehr would make a good Domingo. Or Raymond Cruz, the original Ding in Clear and Present Danger, he did a good job as well.
As for the rest, I would cast maybe a few name actors but leave the rest to new to semi-new faces.