I will give credit where credit is due. Biden was right about two major things:
1. He was against putting ground troops in Afghanistan. His solution to 9/11 was to flatten any Taliban/Al Qaeda asset from the air and from the sea. And if they reappeared, hit 'em again.
2. As you noted ScottinVA, Biden suggested dividing Iraq into three separate homogeneous countries.
I wonder how things would have turned out had Bush II listened to Biden here. It certainly couldn't be any worse than it is now. And a lot of lives and money would have been saved.
Biden tends to favor Iran and the Shia, and both your points 1,2 would weaken Iraq and the Sunnis.
It's so amazingly rare that Biden gets anything right, but yes... those are two points to which I wish Bush had listened. Three homogeneous countries within, say, a loose Iraqi federation could've formed their own governments, with their own militaries, and pursued their own goals. Trying to keep stitched together an artifically formed Iraq was folly.