River Gypsies Guide to N. America (Leland Davis) has a good SE section
North Carolina Rivers & Creeks (also Leland Davis) has some TN runs, espe
cially in the Smokies (doesn't cover the Cumberland Plateau). He's supposedly working on a dedicated TN guidebook too, but I have no idea what the release date would be.
Southeaster Whitwater (Monte Smith, out of print) is another good reference, if you can find a copy.
AW's website has good online info for TN, if you can't find a good print guidebook.