My two favorite performers, Zac Brown and Grace Potter. Zac is lot more rock than country but realized that country was gonna make them a star. Check out some of the recent ZBB shows with Warren Haynes as they perform Pink Floyd's "Comfortably Numb". This ain't your grandaddy's country.
Duet? Grace and Zac. That would be special.
My favorite CMT Crossroads: Jimmy Buffett and Zac Brown. Check out that clip of "Free". 
Back to the original post: How would you like to have stumbled into this bar?
Sonia Leigh is no slouch.... she is a ZB protoge. Good stuff.