I did a short 4 day trip to Cairns and Port Douglas in November 2016. Really enjoyed my stay in both. Cairns as a city is pleasant enough and has a decent variety of restaurants, though it's worth doing some research on them first. The ones nearest the water tend to be the best. A Great Barrier Reef cruise can always be worth doing. We went on the Skyrail, cable car up, and train back down. I thought the cable car was fantastic, and would do it both ways. The train, whilst interesting takes longer. A visit to Palm Cove and a meal there overlooking the beach could be added to the Skyrail.
Port Douglas is great to relax, and wine and dine, but may not be worth going there for just one night.

As far as hotels go we stayed at Hilton Cairns, and Sheraton Port Douglas.
I really liked the Hilton, its an older hotel but has been refurbished and is quite comfortable. If you can get a water view room on the 9th (top) floor its great.
I also recommend the Executive Lounge. Great hosts there and a reasonable food and drink spread, perfect for breakfast and canapes, with a view.
The Sheraton is set in large grounds with many pools for lazing or swimming. It has been completely refurbished, so as far as rooms and public areas go its right up to standard. Service at times can be a bit relaxed!

Hope you enjoy Far North Queensland.