As there are three of you and you are in Sydney for a week, I would suggest an apartment which has cooking and laundry facilities in it. That way, you don't need to eat out for every meal if you don't feel like it. Usually on our visits to Sydney, we stay at a Meriton Suites Hotel. The majority of Meriton Suites have apartments with 2 bedrooms. Meriton Suites Hotels
Or check your favourite hotel booking site for hotels that suit your budget. Note that Easter starts 7th April and for most of Australia, it will be school holidays from then through to 23rd of April so it will be busy and hotels are likely to be more expensive.
There are quite a few threads on this board for Sydney hotels so have a look.