Admiring Specter
Speaking as a Pennsylvania Democrat, I've always admired Arlen Specter's career as one of the most independent Republicans in the Senate. I'm not alone, either: PA has a marked Democrat majority in voter registration, and Specter is from Philly, a very Democratic city - yet he easily wins re-election. (He was Philly's DA when I first moved East, and lost a mayoral race before turning to the Senate).
I wouldn't want him to switch parties - I'd want him to keep working to maintain the occasional moment of lucidity in his own.