Although I must admit that John Roberts is probably the safest/ best choice* for Bush to make regaridng a Supreme Court Chief Justice, I can only imagine what it would feel like to be one of the other justices.
You have the greatest job in the world and each hope to become chief justice. Then, along comes some young gun (whippersnapper) with only 2 years judicial experience and a great resume to become your boss (it reminds me of the Dennis Quaid film In Good Comapany)..
I hope someone will eat with him in the lunch room.
* I would pick Kennedy as the best choice. But, I know Bush sees him as too "moderate." Of course, O'Connor would have been a good choice, if she had wanted to stay.
Of course he will not pick a liberal or moderate (sorry Souter), so we are left with Scalia and Thomas, which would be too controversial and cause hell to break loose in the Senate and airwaves.