We recently stayed at The Goldsborough apartments, which are near the Ibis/Novotel. Not sure how prices compare but we had a 2 bedroom apartment with bedrooms, bathroom and ensuite downstairs, lounge/dining and kitchen and a small
Laundry upstairs. They can organize a shuttle bus service to and from the airport which would be cheaper than a taxi and drops you right at the front door. Was a short walk to the Pyrmont side of Darling Harbour, there is a fantastic playground we found near IMAX, with play equipment, a carousel on weekends and a water play area. DD loved it. We went to the aquarium, which was a short walk also, and Madam Tussauds is next door. We never went there though. The maritime museum is also on that side, and we went through that too. There are decently priced restaurants/cafes in that area and also the Lindt cafe which is, well, YUM!!