It is rare that we get a chance to hear a truly outstanding conductor at Grant Park, but this season's opening concerts this weekend are being led by George Cleve, one of the best in the business. If Cleve is not as well known as, say, Georg Solti, it's for lack of public relations, not for lack of talent. His Chicago Symphony debut two years ago at Ravinia was by far the most memorable in recent years, but since neither CSO nor Ravinia management has leapt at the chance to have him back, he's back at Grant Park. His conducting even there is a pleasure, providing musical nuances and ensemble accuracy rarely heard in that group. His last appearances here were marred by the din from Taste of Chicago, but this year he appears before the chaos ensues. This time we'll have a chance to hear his extraordinary operatic conducting ability in a concert performance of Bizet's Carmen, with a cast that includes Robynne Redmon, Hans Gregory Ashbaker, Julien Robbins, Faith Esham, Virginia Croskery, Richard Cohn, William Watson, and Robert Hovencamp, with the Grant Park Symphony Chorus and the Glen Ellyn Children's Chorus. Saturday, 8 PM, and Sunday, 7 PM, Petrillo Music Shell, Grant Park, Columbus and Jackson; 819-0614.