I'm in LOVE with Port Douglas! It has such a beautiful beach there, much nicer than Cairns and there is heaps to do - reef trips, markets, close to Daintree, etc. Cairns doesn't have much of a beach, but I am a beach girl though so it depends on what you like. Port Douglas has loads of great resorts and restaurants. Palm Cove is nice, but I found it small with no shops and got bored quickly (we stayed in the Mantra Amphora, a great resort). I may have enjoyed it more if we didn't have our DS with us! If it's only for a long weekend though, Palm Cove is a great choice.