I spent a week at the Conrad last year, flying out and return on a WTP award - i definitely would not go anything lower than WTP on this route as it is a long flight.

One thing to consider is also that as you are going to the Conrad you will be connecting to a Seaplane. On your outward flight Conrad will take you to their Conrad Lounge, get you refreshments etc as you wait for your seaplane, you can even take a shower and get a free massage as you wait. On the way back you land in your seaplane but without status are then stuck in the main terminal before your flight departs. This makes it a very long journey back without a proper lounge etc if you are then flying WT / WTP, so if you can go CW one leg I would go on the return home.

Unfortunately you are unlikely to find award availability to CW on this route unless you book a year in advance.

The Conrad is really lovely by the way, make sure to try out the Sunset Grill restaurant.