Four Seasons isn't too bad... Last stay we had a Premier Room there, Oprah View if I recall correctly. Our room must have been recently refurbished - I was more than happy with the furnishings / decor. Public areas need a tidy up though perhaps. You need the corner rooms (Premier and above) - also have stayed in the standard Harbour View and they're very small for anything longer than one night.

Park Hyatt is my favorite in Sydney (last stay late 2009). Westin was as good as Four Seasons but was very busy when I stayed in October 2009 from Wednesday through to Sunday (in particular the business days as it is in a great spot in the CBD).