my experience in Cairns, you are better staying at Global Backpackers if you want to have fun, private rooms, great clean facilities, inc pool, in the heart of the action, young party crowd, Central is newer, and The Waterfront is older, but right on the Esplanade.

The best bar in town, The Pier, and best food/bar on the Esplanade, Rattle 'n Hum, also in Port Douglas.

http://www.globalbackpackers.com.au/

http://www.thepierbar.com.au/

http://www.rattlenhum.com.au/

Have fun, Cairns and Port Douglas are a great time.