The Westin Sydney, the Four Points and the Sheraton on the Park are all within blocks of each other in the Sydney CBD. The Westin is at the corner of Pitt Street and Martin Place in the heart of the financial district, the Sheraton - as the name suggests - overlooks Hyde Park and is located on Elizabeth Street and the Four Points is on Sussex Street if my memory serves me correctly - close to Darling Harbour. For amenities, I would pick the Westin over the Sheraton an the Sheraton over the Four Points.