I prefer Cairns over Airlie Beach. Way much more to do. Airlie beach township consists a a few pubs, restaurants and clothes shops with a ton of accommodation units as most people spend their time out on the Islands where it is very expensive.
Its starting to gather momentum as a back packers town so it now has a bit more low budget accommodation.
Cairns is a city, if you get sick it has a hospital other major infrastructure, and it has major shopping centres and the like, much more accommodating. Also has a Casino, much more to do there.
Post Douglas is more like Airlie Beach, pretty small compared to Cairns.