If you want to stay at Starwood then I believe the Sheraton would be your best bet. It is about a 10 minute walk to the star ferry and then a quick ride across the bay. The ferry terminates right at the convention center. My guess is that it is a bit less than a 30 minute trip in total.
If you want to be really close then the Hyatt or Renaissance, as mentioned above, would be your best bet.
You could also do the W and take the subway. I think it would be slightly less than a 30 minute trip there as well.