Kissinger vs. Brzezinski
Henry Kissinger wrote the book on diplomacy (literally) and Zbigniew Brzezinski was U.S. National Security Advisor for the Carter Administration.
They're two of the elder statesmen of statesmanship. A clash of ideas between these two is a lot more edifying than Hannity vs. Colmes. It's like Gandalf vs. Saruman (you decide who's who).
These days they disagree on everything from the resolution of Iraq II to the rising tensions with Iran, to Iranian President Ahmadinejad's invitation to speak at Columbia.
There's a good summary of their recent disagreements here.
Part one of their appearance with Wolf Blitzer below (part two is here).
And as a bonus, here's Mika Brzezinski, Zbigniew's daughter, refusing to report on Paris Hilton on live TV.