well, I have to give a high recommendation to Silky Oaks as well. As stated, it is in Moss/Daintree and was extremely nice.
No secluded beaches but a feel of riding the resort bikes through town and around hte sugar cane fields is unforgettable. You' d have to check into how close it is to the beach.
But if I were in the Cairns region again I would stay there in a heartbeat. Also the restaurant there was excellent! Sourcream, chive and cheese bread, typing and salivating right now.
As for Port Douglas, actaully I think Trinity Beach was great. We stayed, back in 2001 at a place called the Absolute Beachfront Resort. Or all the hotels, B+Bs and resorts we've stayed, this was the best!
But I think it changed hands and became something like Gaia beach house...? search the net... Its a great, small B+B, right on the beach. If you want private and beach, look no further.
good luck