ANTIQUES ROADSHOW kicks off its visit to Milwaukee, Wisconsin, at the city's traditional German Fest, where host Mark L. Walberg and appraiser Stuart Whitehurst soak up the atmosphere and talk about collectible German beer steins. At the Midwest Airlines Center, collectors are thirsty for information about such treasures as a 1952 Fender Esquire guitar, prized by country and western musicians; a late 19th-century child's sled in the shape of a swan, considered a rare piece of American folk sculpture; and a cliffhanger: an 18th-century desk and bookcase passed down to the owner from his great-grandfather, a former governor of Connecticut, that could be worth as much as $250,000 - or $20,000, if the two pieces are determined to be "married."