Hi Chappy
I am currently in Darwin. Can recommend Robbie Robbins Reserve as a great place to stay. Cheapest around. This is my first time up in Darwin so I dont really know what is normal but to me it is just like a big country town to get around. Great and cheap bus service. Reminds me of Perth when I first moved there in there late 80s. Relaxed feel about the place. People in the main are friendly and engaging. Weather is perfect.
I havent done too Mary touristy things but can recommend the Waterfront Precinct and the old oil tunnels. Museum and Art Gallery is worth a couple of hours. Free entry.
We aren't there this year but have been there in early September in the past and there is a mass exodus of grey nomads throughout August, by the end of August the place is much quieter.