Since she arrived here in 1986 as a cast member of Great Lakes Shakespeare Festival's The Life and Adventures of Nicholas Nickleby, Suzanne Petri has established herself as an actress who can handle classy and brassy with equal ease. Her gritty voice, crisp and witty delivery, and assured stage presence also suit her to musical theater of a certain high style. She made a superb impression when Marshall Productions presented a concert performance of Stephen Sondheim's droll A Little Night Music at the Civic Theatre a few seasons back (she also directed the show). In her performance this weekend at Puszh Studios' cabaret space, Petri will dig into more Sondheim, as well as other darkly stylish, psychologically probing songwriters such as Noel Coward and Kurt Weill; selections from the Dietrich and Piaf songbooks are on the agenda too. Pat Rusk, one of the best show pianists in the city, will provide the accompaniment, and actor Chris Teal will be on hand as a guest vocalist. Friday, 8 PM, Puszh Studios Cabaret, 3829 N. Broadway; 327-0510 or 327-0231.