Thanks, john_ft, m0hamed, and steveholt. I emailed the hotel to inquire about a paid upgrade and they quoted me $350 AUD/night for Harbor View and $500 AUD/night for Opera View. I don't think that's too unreasonable--though it's much higher than what m0hamed recalls them charging in the past, and it does show that the hotel considers the 1 King Bed rooms to be substantially inferior to the rooms they market through ordinary channels. I'm going to do cash and points for a Harbor View (20k points + $695 AUD/night), since I would effective only be getting $0.0175 AUD/point if I booked a 1 King Bed room with 40k points and paid $AUD 350/night for a cash upgrade, which -- at current exchange rates ($0.012 USD/point) -- isn't a good deal for me.

If anyone knows of ways to get discounts on fully paid rooms (non-corporate, as my corporate rate isn't very good), I'm definitely interested in hearing. I'm not holding my breath though.