Alas I'm in Perth, and I have terrible taste in coffee... I mostly work at Starbucks whenever I can. (Or Gloria Jeans, since we don't have Starbucks in Perth.) It's a while since I was last in Sydney.
If you're ever in Singapore I can recommend the 100th Starbucks in the financial district (at The Fullerton Waterboat House). Large space with lots of windows, a great view and not very busy. Terrible WiFi though, so tether to a cheap Singaporean 15GB SIM.