Bored with Johnny Carson? No good guests on Letterman tonight? Need some relief from Arsenio Hall's unctuousness? Try the low-key, no-nonsense approach of Ralph Emery, host of The Nashville Network's talk show Nashville Now. Unlike so many of his colleagues, Emery, a veteran Nashville disc jockey, has nothing to prove. As the host of TNN's highest-rated show and country music's most visible showcase, he has everybody in Nashville wanting to sit on his couch. Emery pulls in the superstars Clint Black, Reba McEntire, and Garth Brooks are all eager to lope on and set a spell. But he's also fond of unexpected guests: When was the last time you saw Jeannie C. Riley (''Harper Valley P.T.A.'') on a talk show? Drawn out by Emery, she proved to be a smart, entertaining guest. So was Shoji Tabuchi, a Japanese singer and fiddler, who did a mean version of ''San Antonio Rose.''
The host is obliged to trade feeble jokes at the start of some shows with a nattering puppet named Shotgun Red, but Emery never gets cute about it in fact, to his credit, he usually looks as if he'd like to wring the neck of the little cowboy-hatted piece of cloth. An aging cool dude with an affable attitude, Emery makes Nashville Now a down-home hoot.