Ahoy there, and such.
Well, they probably are in and amongst the relevant allmusic pages, but look into the Dillards if you haven't. Wheatstraw Suite is the progrssive bluegrass album (or so I understand, and it's gorgeous stuff regardless). The cover the Beatles ("I've just seen a face"), they do wonderful harmonies, and they play a mean goddamn banjo, although slightly moreso on their earlier albums (which are closer to straight bluegrass, but also good).
Anyway, I'll stop pimping them now. Good luck with the show.