Bon Jovi and Sugarland wasn't a bad episode either. Los Lonely Boys and Ronny Milsap is one I really liked, Kid Rock and Hank Williams Jr., Lynard Skynard and Montgomery Gentry and Brad Paisley with John Mayer were all pretty good too.
Probably one of my favorite Cross Country performances:
[ame=http://www.youtube.com/watch?v=5ytldwr79W4]YouTube - John Anderson & Big and Rich - Seminole Wind[/ame]
Cross country is a little different, they pair older and newer country artists up, crossroads pairs non-country and country artists.