What is the difference between Grosvenor Sq. and JW Grosvenor House? The Sg. is a catogory 8 and the JW a cat 7. Trying to figure out a trip for fall and in reading all the posts they seem to zero in on the JW or County Hall. Looking at the highlights at Marriott the Square seems quite nice. Is it the location? Thanks for any clarification you can give me!