I have stayed at Mirambeena a number of times, and have enjoyed my stay on each occasion. It's a comfortable and relaxed place, and like many of the places in Darwin, it has a laid back feel about it. It's centrally located, so just about everything is within walking distance.
The standard of rooms varies significantly, so there should be something to fit most budgets. The prices are on par with other places of similar standard in Darwin, but are a lot higher (especially in the dry season) than other other state capital cities. The service has varied from OK to excellent, the restaurant food has always been good, but to me, the food and drink prices are a bit on the expensive side.

Approximate cost: $280

Travelodge was clean and convenient. Great spot, short walk from town. Opposite Woolworths, doctors and other shops. Pools on site were pretty great actually, and bar/menu available pool side as well. Rooms are standard, clean but "sterile" feeling without much character but fine. Good deals to be had on Wotif and upgrades available in wet season for little cost.