Unpretentious elegance and some of the finest cuisine in the city make for a posh Four Seasons dining experience.. The formal dining room is softly elegant, with plush carpet, upholstered armchairs and linen-swathed tables set with Wedgwood china. Jackets are recommended, and the menu is pricey, but the atmosphere is far from stuffy. Seasons' excellent, tastefully presented French fare makes it one of Chicago's finest dining destinations. Dishes on the ever-changing menu might include seductive pancetta-roasted salmon atop asparagus and black truffle gnocchi in asparagus broth or succulent, peppery seared antelope with delicate celery root puree. Sunday brunch features six differently themed buffet stations, including Asian, Mediterranean, seafood and a deluxe breakfast station offering made-to-order omelettes. For dessert, Seasons calls its milk chocolate pyramid the "Eighth Wonder of the World," and for chocolate freaks, it may well be.…