The American Express Lounge is pretty good with plenty of tables and couch, buffet style lunch/dinner, coffee, drinks and good wifi.

Not sure how much they charge but most Amex cards get complimentary access to the lounge.

It's in Terminal 1. Hope this helps.

Reference:
https://www.sydneyairport.com.au/fin...3A61242132C%7D

https://amexnetwork.com.au/goodgoing/