I am a long time lurker and have benefited from a lot of your advice - thanks very much.

If you do not have access to the club lounge (but it sounds like you will if you have a suite) at the IC Sydney and are unable to check in early, they do offer a guest lounge (I think it is on the 10th or 11th floor and overlooks Sydney Harbour). It contains a large lounge with TV and newspapers, desk, kitchen with tea & coffee making facilities and bathroom with shower etc.

We filled in a leisurely couple of hours there late last year while we waited for our room. It is a beautiful hotel and minutes from Circular Quay.