I spent 10 years in Darwin... grew up there pretty much, from age 8 to 18. My parents finally sold their house and moved south in 2007. I still miss it, particularly the wet season storms!

Darwin has a lovely vibe. The humidity is definitely manageable, although you may want to avoid planning to do much outdoors between midday and 4pm. As the others have said, there are a lot of swimming pools around, and houses either have airconditioning or ceiling fans. One of my first memories of arriving in Darwin was of how excited my sister and I were to find it was warm when it rained! We spent most of our time swimming, and adapted to the climate pretty quickly.

Very excited for you!