If you fly in to Cairns at a convenient hour you might want to take off on your Great Barrier Reef Drive adventure straight away, but if you get in a bit late then it could be better to find some accommodation in Cairns first to have a good rest and start your drive fresh the next morning. At the end of your stay in far north Queensland you could also need some accommodation in Cairns if you have an early flight, as Port Douglas is a full hour from the airport and Cape Tribulation 2.5 hours.