Darwin
Melaleuca on Mitchell
This hostel is located in the centre of Darwin and very popular. They have an awesome bar with pool and rooftop terrace where you can party the whole day. The rooms are very spacious and clean (with enough powerplugs!). I stayed on the third floor which is completely for girls only. The staff is very friendly and can help you with anything. The bathrooms and kitchen is good too, very clean and enough space for everybody.

Alice Springs
Haven Backpackers
I absolutely loved Haven Backpackers! It is really really clean and a lot space for entertainment. There is a movieroom and terraces all around the hostel as well as a barbecue area and a pool. I slept in a private room the whole week and had my own bathroom, microwave and fridge which was awesome! They organized all kinds of tours for me with Alice Wanderer so I had the best introduction to Alice Springs and the surroundings. I had a day tour to the MacDonnell ranges and got to see the beautiful gorges and learned everything about the indigenous culture. I also received a 2day buspass to explore the attractions of Alice Springs like School of the Air, the Flying Doctors and the Art Gallery. The hostel has a very friendly atmosphere and makes you feel right at home as soon as you arrive.