I Havent used it in a number of yeas but the Old Sheraton..now Stamford near the Dom terminals had a reasonable one.There is also one about 5 mins away by car near the Mitre 10 store on Gardiners rd which has a pool etc...cant remember the bame though.....or if you can borrow a QF ID apparently there is a resonable Gym on the Qantas Jet base